Hagia Sophia (Turkish: Ayasofya; Ancient Greek: Ἁγία Σoφία, romanized: Hagía Sophía; Latin: Sancta Sapientia; meaning ‘Holy Wisdom’) is one of the most historically significant structures in Istanbul. 125 Initially erected as a Byzantine church, it was the final of three consecutive churches constructed on the same location by the Eastern Roman Empire. Completed in AD 537, it included one of the oldest fully pendentive domes and became the biggest enclosed space in the world. Esteemed as the apex of Byzantine architecture, its innovative design has profoundly influenced the history of construction.

From its consecration in AD 360 until 1453, the edifice primarily served as an Eastern Orthodox church, with a brief interval (1204–1261) under Latin Catholic dominion during the Fourth Crusade. After the Ottoman conquest of Constantinople in 1453, it was transformed into a mosque and retained this status until 1935, when it was designated as a museum in accordance with the secular policies of the Republic of Turkey. In 2020, its status was revised, reinstating its function as an operational mosque, a decision that provoked international conversation.

The current edifice of Hagia Sophia was commissioned by Byzantine Emperor Justinian I and completed between 532 and 537 as the Christian cathedral of Constantinople. Conceived by the Greek mathematicians Isidore of Miletus and Anthemius of Tralles, the edifice was officially designated as the Church of God’s Holy Wisdom (Greek: Ναὸς τῆς Ἁγίας τοῦ Θεοῦ Σοφίας, romanized: Naòs tês Hagías toû Theoû Sophías). This was the third church of that name at the location, succeeding a predecessor that was obliterated during the Nika Riots. Serving as the seat of the Ecumenical Patriarch of Constantinople, it retained the designation as the world’s largest cathedral for almost a thousand years, until the Seville Cathedral was completed in 1520.

The Hagia Sophia established a benchmark for Orthodox ecclesiastical architecture, impacting numerous edifices, including the Hagia Sophia of Thessaloniki, Panagia Ekatontapiliani, and various Ottoman mosques such as the Şehzade Mosque, Süleymaniye Mosque, Rüstem Pasha Mosque, and Kılıç Ali Pasha Complex. For nearly a millennium, it functioned as the nucleus of Eastern Orthodox Christianity, consecrated to Holy Wisdom. Regarded as an unmatched cultural and architectural emblem of the Byzantine and Orthodox realms, it saw a significant historical religious division—the formal excommunication of Patriarch Michael I Cerularius in 1054, signifying the onset of the East-West Schism. In 1204, during the Fourth Crusade, it was converted into a Roman Catholic cathedral under the Latin Empire, but was returned to Orthodox use during the Byzantine reconquest in 1261. Among its numerous historical personalities, Enrico Dandolo, the Venetian Doge who planned the Fourth Crusade and the Sack of Constantinople, was entombed within its walls.

Following the Ottoman conquest of Constantinople in 1453, Sultan Mehmed II mandated its transformation into a mosque. It served as the principal mosque of Istanbul until the establishment of the Sultan Ahmed Mosque in 1616. The shift entailed substantial alterations, including the elimination of Christian imagery such as bells, the altar, iconostasis, and baptistery, while mosaics representing Jesus, Mary, and Christian saints were either obliterated or covered with cement. Islamic architectural enhancements comprised a mihrab, minbar, and four prominent minarets. Concurrently, the Ecumenical Patriarchate transferred to the Church of the Holy Apostles, which subsequently became the city’s new Orthodox cathedral.

The Hagia Sophia served as a mosque until 1931, when it was shuttered for repair. In 1935, it was reestablished as a museum following the secularizing policies of the Republic of Turkey and continued to be the country’s most frequented tourist destination as of 2019. In July 2020, the Turkish Council of State annulled the 1934 ruling that had classified it as a museum. The judgment deemed the reclassification illegal under both Ottoman and Turkish legal systems, referencing the site’s original waqf endowment by Sultan Mehmed II, who classified it as a mosque. Proponents defended the decision as a restoration of its legitimate status, although it elicited widespread condemnation from UNESCO, the World Council of Churches, and several global leaders, while receiving endorsement from numerous Muslim authorities both in Turkey and internationally.

The Hagia Sophia represents the cultural and theological transformation of Istanbul, formerly the capital of three significant empires. Designated as a UNESCO World Heritage Site, it stands as one of the most important monuments of global heritage. Reconstructed numerous times, it stands as a witness to the aspirations of sovereigns and the fluctuating currents of history. Established by Emperor Justinian, the Church of Holy Wisdom stood as the greatest cathedral in the world for a thousand years, exemplifying remarkable engineering and design.

Following the conquest of Constantinople by the Ottomans in 1453, the Hagia Sophia was converted into the city’s inaugural imperial mosque. Sultan Mehmed II commenced comprehensive renovations, fortifying the edifice with buttresses and incorporating Islamic features including minarets, mihrabs, minbars, and ornamental calligraphy. Christian symbolism was obscured by layers of plaster, while Ottoman decorations transformed its artistic magnificence. Throughout the years, more improvements were made, including the establishment of a madrassa, a public soup kitchen (imaret), fountains (shadirvans), and a comprehensive library.

Beyond a mosque, Hagia Sophia represents a growing history and an architectural masterpiece that embodies centuries of human ingenuity. In 1934, the Republic of Turkey converted it into a museum, along with the nation’s secular objectives. Nonetheless, a pivotal milestone occurred in 2020 when it was officially restored as a mosque, rekindling discussions regarding its significance in contemporary Turkey.

By the mid-fifteenth century, the historic Byzantine capital had fallen under Ottoman control, with the Hagia Sophia converted for Islamic worship. The first Friday prayers held within its confines solidified its new identity. Despite the structure’s deterioration due to neglect and conflict, restoration initiatives revitalized its revered interiors. Instead of obliterating its history, the Ottomans concealed Christian artifacts while maintaining the building’s structural integrity.

Throughout this era, the Hagia Sophia had significant improvements. The four prominent minarets, now emblematic, were incorporated, while repairs in the mid-nineteenth century featured large medallions etched with Arabic calligraphy, as well as Neo-Byzantine columns and Ottoman marble decorations. The 1935 conversion into a museum signified a new era, illustrating Turkey’s adoption of secularism. In 2020, following decades of popular advocacy, it was reclassified as a mosque, reinforcing its significance in the nation’s changing identity.

Few structures in human history have undergone such significant transformations as the Hagia Sophia. It exemplifies the rise and fall of empires, the merger of Christianity and Islam, and the inexorable passage of time, serving as a unique representation of architectural synthesis. From its Byzantine origins to its Ottoman reinterpretation, it remains a living witness to Istanbul’s vibrant history, where centuries-old traditions coalesce in harmonic splendor.

Architecture

The Hagia Sophia is a stunning and lasting testament to the brilliance of Byzantine architecture. The expansive interior, adorned with detailed mosaics, soaring marble columns, and lavish decorative elements, showcases a time of remarkable artistry. Commissioned by Emperor Justinian, it was an extraordinary architectural achievement in its era, maintaining the distinction of being the world’s largest cathedral for almost a thousand years—until the Seville Cathedral in Spain was completed.

The structure is built using masonry techniques, utilizing brick and mortar in proportions where the joints measure 1.5 times the width of the bricks. The mortar is composed of a blend of sand and finely crushed ceramic fragments, a method that harks back to Roman concrete—an early forerunner to contemporary cement materials. Furthermore, the significant incorporation of iron through clamps and ties strengthens the structure, improving its durability.

Justinian’s grand basilica embodies the peak of Late Antique architectural traditions while also marking the beginning of Byzantine design excellence. Its significant impact reached far beyond the Byzantine domain, influencing the liturgical and architectural practices of Eastern Christianity, Western Christendom, and even Islamic monumental designs.

Structural Composition and Geometric Design

The vast interior features a complex spatial layout. The nave features a grand central dome that rises to an impressive height of 55.6 meters (182 feet 5 inches) above the floor, with its weight elegantly supported by an arcade of 40 arched windows. Over time, structural interventions have led the dome to take on a slightly elliptical shape, with its diameter varying between 31.24 and 30.86 meters (102 feet 6 inches and 101 feet 3 inches).

At both the western entrance and the eastern liturgical side, large arched openings lead into semi-domes that reflect the diameter of the central dome. These are complemented by smaller semi-domed exedrae, creating a cascading hierarchy of domed elements. This elegant design culminates in a spacious oblong chamber, topped by the magnificent central dome, resulting in an impressive 76.2-meter (250-foot) span.

Mathematical Precision in Construction

The geometric principles that underpin the construction of the Hagia Sophia are thought to be influenced by the mathematical works of Heron of Alexandria, a groundbreaking Hellenistic mathematician from the 1st century AD. His methodologies offered effective solutions for the significant challenge of covering extensive areas with large-scale vaults. According to researchers Svenshon and Stiffel, Heron’s prescribed values influenced the architects, especially through a numerical system based on side-and-diagonal number progressions. This system, as seen in ancient Babylonian cuneiform texts, utilizes proportional relationships where a square’s side measures 12 units and its diagonal measures 17.

The central square of the Hagia Sophia features four sides, each extending roughly 31 meters, a dimension previously believed to correspond to 100 Byzantine feet. Nonetheless, Svenshon subsequently suggested that the true measurement is 99 feet—an alteration that corresponds with the 70:99 ratio found in ancient mathematical sequences. This precise measurement yields a diagonal length of 140, a practical figure for carrying out the dome’s engineering with exact mathematical accuracy.

Floor

The Omphalion, a stunning marble section of the Hagia Sophia’s floor, carries deep historical importance as the coronation site of Byzantine emperors. The stone flooring of the structure, which dates back to the 6th century, quietly reflects centuries of imperial magnificence. After the initial collapse of the vaulted ceiling, fragments of the broken dome lay strewn across the original Justinianic floor. In 558, the dome underwent reconstruction, with a new layer added over the existing debris. From this moment onward, the flooring transformed into a vital element of the church’s sacred rites, with various-colored marbles and stones marking significant locations within the liturgical space.

The floor, primarily made of Proconnesian marble from Marmara Island in the Sea of Marmara, showcases the grandeur of Constantinople’s architectural heritage. Furthermore, Thessalian verd antique marble, sourced from Roman Greece, adorns the structure, its rich green veins streaming through the nave like meandering rivers.

Writers and poets have often celebrated the floor’s enchanting beauty, frequently comparing it to an expansive sea. Paul the Silentiary, a Byzantine poet from the time of Justinian, imagined the ambo and its connecting pathway to the sanctuary as an island floating in a vast ocean. An account from the 9th century likened the floor to rolling waters, a perspective mirrored by Michael the Deacon in the 12th century. During the Ottoman conquest of Constantinople, Sultan Mehmed II reportedly ascended the galleries to admire its magnificence—chronicler Tursun Beg depicted it as a tumultuous, frozen sea. Ottoman authors lauded its aesthetic beauty, with Tâcîzâde Cafer Çelebi poetically likening the marble waves to the gentle undulations of a real ocean. On July 22, 2020, this historic floor was covered by a carpet.

Narthex and Portals

The Imperial Gate, a magnificent entrance between the exo- and esonarthex, was once the sole passage reserved for the Byzantine emperor. A long ramp, starting from the northern area of the outer narthex, rises to the upper gallery, offering a view of the expansive interior.

Upper Gallery

The horseshoe-shaped upper gallery, known as the matroneum, encircles the nave on three sides and is interrupted only by the apse. This space was traditionally reserved for the Empress and her retinue. The gallery showcases a variety of mosaics, with the most exquisite pieces located in its southern section.

The northern gallery features an extraordinary artifact of medieval mystery: runic inscriptions thought to have been carved by the Varangian Guard. The exterior surfaces of Hagia Sophia exhibit signs of structural deterioration due to natural disasters, leading to comprehensive studies utilizing ground-penetrating radar (GPR). The investigations have uncovered areas of structural weakness within the gallery and highlighted a slight deviation in the curvature of the vault dome from its original alignment.

Dome

The impressive dome of Hagia Sophia has fascinated historians, architects, and engineers, thanks to its groundbreaking design. The dome, supported by four spherical triangular pendentives—an architectural innovation of its time—effectively distributes its immense weight downwards, reducing lateral forces. Until the completion of St. Peter’s Basilica, this remarkable structure held the title of the world’s largest pendentive dome.

The dome measures 32.6 meters (107 feet) in diameter and has a thickness of only 0.61 meters (2 feet), constructed from brick and mortar. The lightweight aggregate, crucial for its construction, was selected over cut stone because of its enhanced malleability and ability to accommodate large-scale applications. Architectural scholar Rowland Mainstone suggested that the thickness of the vaulting shell is improbable to surpass that of a single brick.

However, the considerable weight of the dome presented an ongoing challenge. The original structure completely fell apart after an earthquake in 558. A second iteration, constructed by Isidore the Younger in 563, included 40 reinforcing ribs and was raised by an additional 6.1 meters (20 feet) to reduce lateral stress. Nevertheless, sections of this later dome also experienced structural failure. As of 2021, only the northern and southern sections, which consist of a total of 14 ribs, remain from the 562 reconstruction.

The challenges were worsened by construction flaws. The builders applied an excessive amount of mortar compared to the bricks, which compromised the overall structural integrity. The mortar had not completely cured when further layers were added, leading to walls that leaned outward once the dome’s significant weight was applied. Isidore the Younger had to strengthen and adjust these walls prior to rebuilding the dome, utilizing a ribbed, umbrella-like structure to more effectively distribute its weight through the pendentives and into the foundation.

The celestial glow of Hagia Sophia, produced by the interplay of light within the nave, further amplifies the dome’s illusion of levitation. This enchanting effect is created by forty windows surrounding its base, which not only diminishes structural mass but also fills the interior with light.

Buttresses

Throughout the centuries, various buttresses have been added to strengthen the structure. The western flying buttresses, frequently credited to Crusader alterations, actually trace their roots back to the Byzantine period. This highlights the exceptional skill of Roman architecture in this technique, as seen in the Rotunda of Galerius in Thessaloniki and the octagonal Basilica of San Vitale in Ravenna. During Ottoman rule, further reinforcements were implemented, with the renowned architect Mimar Sinan supervising the construction of 24 buttresses to strengthen the structure.

Minarets

The minarets, symbolic of Hagia Sophia’s evolution from cathedral to mosque, were later Ottoman additions not present in its original Byzantine architecture. The first minaret, designed to aid in the call to prayer (adhan) and public announcements, was built of wood and placed atop a half-dome during the reign of Sultan Mehmed II, although it has since been lost to time. The oldest existing minaret, made of red brick, originates from the time of either Mehmed II or his successor, Bayezid II. The last three, made of white limestone and sandstone, feature Bayezid II’s slender northeast minaret along with two grand western minarets commissioned by Selim II and crafted by the esteemed Ottoman architect Mimar Sinan. Soaring to a height of 60 meters (200 feet), these majestic spires harmoniously blend with the magnificence of Hagia Sophia’s central structure. Throughout the centuries, elaborate decorations were added, with each version showcasing the artistic values of its time.

Significant Elements and Ornamentation

During the reign of Emperor Justinian, the interior embellishments of the Hagia Sophia showcased intricate, abstract motifs that adorned the marble-clad walls and floors, while shimmering mosaics decorated the expansive vaults. In the spandrels of the bema, the archangels Gabriel and Michael are still clearly visible among these mosaics. While primarily non-figurative, certain representational artworks were already evident, as recorded in the late 6th-century ekphrasis by Paul the Silentiary, known as Description of Hagia Sophia. The spandrels of the gallery feature intricately inlaid opus sectile, showcasing precisely cut pieces of white marble that create delicate representations of flora and fauna, all set against a backdrop of black marble. As time progressed, more figurative mosaics were added, yet they were destroyed during the iconoclastic upheaval that occurred between 726 and 843. The existing mosaics are from the post-iconoclastic period.

In addition to mosaics, the latter half of the 9th century witnessed the emergence of extensive figural iconography: a majestic depiction of Christ adorned the central dome, while Eastern Orthodox saints, prophets, and Church Fathers were featured in the tympana below. Historical figures associated with the sacred edifice, including Patriarch Ignatius, were likewise commemorated. The galleries displayed scenes from the Gospels, and Emperor Basil II commissioned massive seraphim with six wings to be painted on each of the four pendentives. The Ottomans subsequently adorned their faces with golden stars; however, in 2009, one was returned to its original state.

The Loggia of the Empress

Located at the heart of the Hagia Sophia’s gallery, right above the Imperial Gate and opposite the apse, the Loggia of the Empress provided a prime viewpoint for the empress and her entourage to witness the holy ceremonies taking place beneath them. A circular disc of verd antique, a unique green-hued marble, indicates the exact spot where the empress’s throne was situated.

Lustration Urns

Two grand lustration urns, carved from solid blocks of marble, were brought from Pergamon at the command of Sultan Murad III. Originating in the Hellenistic period, these urns were employed in ritual purification ceremonies.

The Marble Door

Located in the southern upper gallery, the Marble Door was solely accessed by members of ecclesiastical synods. Beautifully decorated with designs of fruits and fish, it was said to carry deep symbolic meaning, with one side symbolizing heaven and the other, hell. The door opened into a room intended for serious discussions among patriarchs and important theological decisions.

The Nice Door

The Nice Door, considered the oldest architectural element of the Hagia Sophia, originates from the 2nd century BC. The intricate reliefs, showcasing geometric patterns and botanical motifs, are thought to have come from a pagan temple located in Tarsus, Cilicia (now known as Mersin Province, Turkey). In 838, Emperor Theophilos incorporated it into the structure, and it currently resides at the southern exit of the inner narthex.

The Imperial Gate

The Imperial Gate, the largest and most striking entrance of the Hagia Sophia, was designated solely for the Byzantine Emperor and his immediate retinue. Standing at around seven meters tall, historical Byzantine texts claim that the wood utilized in its construction was obtained from Noah’s Ark. This monumental door, dating back to the 6th century, was vandalized in April 2022, an act that drew international condemnation. The Greek Foreign Ministry condemned the desecration, while Turkish authorities initiated an investigation following reports that someone had removed a piece of the door.

The Wishing Column

Situated in the northwest part of the building, this intriguing column, referred to as the Perspiring Column, Sweating Column, or Crying Column, showcases a central opening surrounded by bronze. According to legend, the continuous moisture is attributed to Saint Gregory Thaumaturgus in the year 1200. It is believed that making contact with the column’s moisture has healing effects.

The Viking Inscription

A 9th-century inscription created by a Viking mercenary has been found within the southern precinct of the Hagia Sophia. The runic text clearly indicates: Halvdan was here, providing an intriguing record of the Norse warriors who served the Eastern Roman Empire.

Mosaics of the Hagia Sophia

Early Christian Mosaics and Byzantine Iconoclasm

The earliest mosaics that embellish the Hagia Sophia originate from the reign of Justin II, showcasing non-figurative designs typical of that period. Nonetheless, the most extraordinary mosaics emerged in the 10th and 12th centuries, after the eras of Byzantine Iconoclasm, which had led to the obliteration of numerous religious images.

In 1204, the Latin Crusaders’ Sack of Constantinople resulted in the widespread looting of the city’s Byzantine treasures, notably the golden mosaics of the Hagia Sophia. A significant number of these priceless artifacts were brought to Venice under the guidance of Doge Enrico Dandolo, who had coordinated the conquest in partnership with Prince Alexios Angelos, the son of the ousted Byzantine emperor.

Ottoman Transformation and 19th-Century Restoration

Following the Ottoman conquest in 1453, the Hagia Sophia was transformed into a mosque, and its mosaics were progressively covered with layers of plaster to comply with Islamic restrictions on representational imagery. Nevertheless, records from the 17th century suggest that certain Christian images continued to be seen.

Between 1847 and 1849, the restoration led by Swiss-Italian architects Gaspare and Giuseppe Fossati saw Sultan Abdulmejid I granting permission for the documentation of the mosaics. While the Fossati brothers meticulously documented the imagery, they chose not to restore the mosaics, opting instead to repaint over them. Among their findings were the hexapteryga—six-winged angelic figures—on the eastern pendentives, which they subsequently concealed once again. The Fossati archives serve as an essential historical record, safeguarding information about many mosaics that were either harmed or completely lost in the catastrophic 1894 Istanbul earthquake.

A notable mosaic found in the Fossati records is Christ Pantocrator, shown within a circular frame, probably embellishing the central dome. This mosaic was ultimately hidden under Islamic calligraphy, which declares God as the light of the universe. Currently, these precious sketches are preserved in the Archive of the Canton of Ticino.

Notable Mosaics of the Hagia Sophia

Imperial Gate Mosaic

Located above the Imperial Gate—historically designated for the emperor—this mosaic, dating back to the late 9th or early 10th century, depicts an emperor (probably Leo VI or Constantine VII) kneeling before Christ Pantocrator, who is seated on a throne, offering a blessing and holding an open book. The manuscript contains inscriptions from John 20:19 and John 8:12. On either side of Christ are medallions featuring the images of the Archangel Gabriel and the Virgin Mary.

Southwestern Entrance Mosaic

This mosaic, dating from the reign of Basil II, was rediscovered during the Fossati restorations of 1849. The artwork depicts the Virgin Mary seated with the Christ Child, accompanied by Emperor Constantine, who presents a model of the city, and Emperor Justinian I, who offers a model of the Hagia Sophia. The head of the Virgin is accompanied by inscriptions featuring the Greek abbreviations for “Mother of God.”

Apse Mosaic

The mosaic in the semi-dome of the apse stands as a highly esteemed representation of Byzantine art, showcasing the Virgin Mary on a jeweled throne, cradling the Christ Child. The baby’s clothing is made from golden tesserae, shining with heavenly light. Travelers like Guillaume-Joseph Grelot (1672) and Cornelius Loos (1710) provide historical records that confirm its existence prior to its subsequent concealment by Ottoman authorities. The mosaic was rediscovered between 1847 and 1848, and it was uncovered again in the 1930s by Thomas Whittemore.

Experts engage in discussions regarding the exact date of its creation. Some attribute it to the period following the end of Byzantine Iconoclasm, potentially during the patriarchate of Photius I (858–886), while others propose a later date, suggesting that an earlier standing image of the Virgin may have been replaced after the earthquakes of the 14th century. Recent studies of a hexaptych menologion panel from St. Catherine’s Monastery indicate that the depiction closely resembles the apse mosaic in its current form, suggesting its presence by at least the 11th or 12th century.

Later Byzantine and Post-Byzantine Mosaics

Emperor Alexander Mosaic

Situated in a softly illuminated corner on the second floor, this mosaic depicts Emperor Alexander adorned in his full regalia, holding a scroll and an orb. Thought to be lost in the 1894 earthquake, it was found again in 1958, hidden under layers of paint instead of plaster.

Empress Zoe Mosaic

This mosaic, dating back to the 11th century, showcases Christ Pantocrator at its center, accompanied by Emperor Constantine IX Monomachos and Empress Zoe, who are both presenting symbolic offerings. Over time, changes to the mosaic indicate earlier depictions of Zoe’s former husbands, whose facial features were subsequently modified to represent the current ruling couple.

Comnenus Mosaic

This mosaic, dated to 1122, depicts the Virgin Mary with the Christ Child, while Emperor John II Comnenus and Empress Irene of Hungary present gifts. Alexius, their eldest son, is portrayed on a nearby pilaster. The depiction of Empress Irene is especially vivid, featuring braided blond hair, rosy cheeks, and gray eyes that highlight her Hungarian roots.

Deësis Mosaic

The Deësis mosaic, created in 1261, is regarded as the height of Byzantine artistry within the Hagia Sophia, symbolizing the conclusion of Latin rule and the revival of Eastern Orthodox Christianity. Christ Pantocrator is portrayed alongside an earnest Virgin Mary and John the Baptist, pleading for divine mercy on behalf of humanity. The craftsmanship showcases a refined elegance reminiscent of the Renaissance within Byzantine iconography.

Northern Tympanum Mosaics

These mosaics, preserved by their prominent location, illustrate revered figures like Saints John Chrysostom and Ignatius of Constantinople, dressed in white robes with crosses, and holding beautifully adorned Gospels. Numerous other mosaics in the tympana, however, were destroyed due to frequent seismic activity.

20th-Century Restoration and Conservation Efforts

During the 1930s, the Byzantine Institute of America, under the direction of Thomas Whittemore, revealed numerous mosaics that had been concealed beneath layers of plaster. Although numerous significant artworks were unveiled, some basic crosses remained hidden. The ongoing challenge of restoration remains a nuanced balancing act between Christian iconography and Islamic art. The debate surrounding the potential removal of Islamic calligraphy in the dome to reveal the Pantocrator mosaic beneath—if it still exists—has become particularly contentious.

The structural integrity of the Hagia Sophia has been compromised by natural degradation, worsened by salt crystallization resulting from rainwater infiltration. Conservationists highlight the significance of redirecting surplus moisture to avert additional harm.

Recent geophysical studies using LaCoste-Romberg gravimeters have investigated subsurface structures beneath the Hagia Sophia, uncovering concealed cavities that could have significantly contributed to the building’s strength against seismic events. The findings reveal that the monument’s foundation is situated on a natural rock slope, providing valuable insight into its lasting stability in the face of centuries of earthquakes.

The Hagia Sophia stands as a remarkable example of artistic and architectural excellence, with its mosaics narrating centuries of change, devotion, and endurance.

Architectural Legacy of the Hagia Sophia

The profound impact of the Hagia Sophia spans centuries, influencing the architecture of countless religious structures around the globe. The Church of Saint Sava in Belgrade stands out among its notable successors, reflecting its original design, characterized by a grand central dome that commands a symmetrical square base.

Numerous buildings have embraced the distinctive design of the Hagia Sophia, featuring a magnificent dome supported by pendentives and accompanied by two semi-domes to ensure structural equilibrium. In Byzantine architecture, this influence is clear in the Hagia Sophia of Thessaloniki and the Hagia Irene, the latter experiencing substantial renovations under Emperor Justinian to include a dome similar to its Constantinopolitan counterpart.

The Ottoman Empire, profoundly influenced by the Hagia Sophia, incorporated its spatial principles into the design of mosques. The Süleymaniye Mosque and the Bayezid II Mosque illustrate this legacy, as Ottoman architects frequently enhanced the concept by surrounding the central dome with four semi-domes rather than two. The Sultan Ahmed Mosque, the Fatih Mosque, and the New Mosque in Istanbul illustrate this adaptation, showcasing vast colonnaded courtyards—paying tribute to the Hagia Sophia, whose courtyard has long since disappeared.

The Neo-Byzantine movement continued to advance the architectural language of the Hagia Sophia. The Kronstadt Naval Cathedral, Holy Trinity Cathedral in Sibiu, and the Poti Cathedral carefully mirror its internal proportions, with the Kronstadt Naval Cathedral reaching an almost exact scale and spatial arrangement. The marble revetments also reflect the aesthetic of its Byzantine predecessor.

Several buildings, including the Church of Saint Sava, adopt the Ottoman choice of four semi-domes instead of two, while others, like the Catedral Metropolitana Ortodoxa in São Paulo and the Église du Saint-Esprit in Paris, alter the original design by replacing the tympanums beneath the central dome with shallow semi-domes. The latter structure, while impressive, is two-thirds the size of the Hagia Sophia.

Hybrid designs also arise, blending the influence of the Hagia Sophia with the Latin cross plan. The Cathedral Basilica of Saint Louis in St. Louis features semi-domes in its transept, and its column capitals and mosaics closely resemble Byzantine prototypes. Additional significant examples are the Alexander Nevsky Cathedral in Sofia, St. Sophia’s Cathedral in London, Saint Clement Catholic Church in Chicago, and the Basilica of the National Shrine of the Immaculate Conception.

The Hagia Sophia has significantly influenced synagogue design, extending its impact beyond just Christian and Islamic architecture. The Congregation Emanu-El in San Francisco, the Great Synagogue of Florence, and the Hurva Synagogue all feature elements that draw inspiration from their impressive spatial dynamics and architectural creativity.