Hagia Sophia Istanbul (Ayasofya) I

It was constructed in five years, from 532 to 537, at the orders of Emperor Justinian I and designed by Isidore of Miletus.[

Description

Hagia Sophia is covered by a central dome with a diameter of 31 meters (102 feet) and 56 meters high, slightly smaller than the Pantheon's. The dome seems rendered weightless by the unbroken arcade of arched windows under it, which help flood the colourful interior with light.

The dome is carried on pendentives — four concave triangular sections of masonry which solve the problem of setting the circular base of a dome on a rectangular base. At Hagia Sophia the weight of the dome passes through the pendentives to four massive piers at the corners. Between them the dome seems to float upon four great arches.

At the western (entrance) and eastern (liturgical) ends, the arched openings are extended by half domes carried on smaller semidomed exedras. Thus a hierarchy of dome-headed elements builds up to create a vast oblong interior crowned by the main dome, a sequence unexampled in antiquity. All interior surfaces are sheathed with polychrome marbles, green and white with purple porphyry and gold mosaics, encrusted upon the brick. On the exterior, simple stuccoed walls reveal the clarity of massed vaults and domes.

Construction

A section of the original architecture of Hagia SophiaNothing remains of the first church that was built on the same site during the 4th century. Following the destruction of the first church, a second was built by Constantius II, the son of Constantine I, but was burned down during the Nika riots of 532. The building was rebuilt under the personal supervision of Emperor Justinian I and rededicated on December 27, 537.

Justinian chose Isidore of Miletus and Anthemius of Tralles, a physicist and a mathematician, as architects; Anthemius, however, died within the first year. The construction is described in Procopius' On Buildings (De Aedificiis). The Byzantine poet Paul the Silentiary composed an extant poetic ekphrasis, probably for the rededication of 563, which followed the collapse of the main dome.

After the great earthquake in 989, which ruined the dome of St Sophia, the Byzantine government sent for the Armenian architect Tirdat, creator of the great churches of Ani and Agine, to repair the dome.

Hagia Sophia is one of the greatest surviving examples of Byzantine architecture. Of great artistic value was its decorated interior with mosaics and marble pillars and coverings. The temple itself was so richly and artistically decorated that Justinian proclaimed "Solomon, I have surpassed thee!". Justinian himself had overseen the completion of the greatest cathedral ever built up to that time, and it was to remain the largest cathedral for 1,000 years up until the completion of the cathedral in Seville.

Justinian's basilica was at once the culminating architectural achievement of late antiquity and the first masterpiece of Byzantine architecture. Its influence, both architecturally and liturgically, was widespread and enduring in the Eastern Orthodox, Roman Catholic, and Muslim worlds alike. Under Justinian's orders, eight Corinthian columns were disassembled from Baalbek, Lebanon and shipped to Constantinople for the construction of Hagia Sophia.[4]

Interior of the Hagia Sophia, February 2007The dome of Hagia Sophia has spurred particular interest for many art historians and architects because of the innovative way the original architects envisioned the dome. The dome is supported by pendentives which had never been used before the building of this structure. The pendentive enables the round dome to transition gracefully into the square shape of the piers below. The pendentives not only achieve a pleasing aesthetic quality, but they also restrain the lateral forces of the dome and allow the weight of the dome to flow downward.

Although this design stabilizes the dome and the surrounding walls and arches, the actual construction of the walls of Hagia Sophia weakened the overall structure. The bricklayers used more mortar than brick, which, of course, constitutes a weak wall. The structure would have been more stable if the builders at least let the mortar cure before they began the next layer; however, they did not do this. When the dome was placed atop the building, the weight of the dome caused the walls to lean outward because of the wet mortar underneath. When Isidorus the Younger rebuilt the original dome, he had to first build up the interior of the walls so that they were vertical in order to support the weight of the new dome. Another probable change in the design of the dome when it was rebuilt was the actual height of the dome. Isidore the Younger raised the height of the dome by approximately twenty feet so that the lateral forces would not be as strong and the weight of the dome would flow more easily down the walls.

A second interesting fact about the original structure of the dome was how the architects were able to place forty windows around the base of the dome. Hagia Sophia is famous for the mystical quality of light that reflects everywhere in the interior of the nave, which gives the dome the appearance of hovering above the nave. This design is possible because the dome is shaped like a scalloped shell or the inside of an umbrella with ribs that extend from the top of the dome down to the base. These ribs allow the weight of the dome to flow between the windows, down the pendentives, and ultimately to the foundation.

The anomalies in the design of Hagia Sophia show how this structure is one of the most advanced and ambitious monuments of late antiquity.