The Hagia Sophia or simply the Great Church was the cathedral of Constantinople, the center of Constantinian city, the first hill, near the Grand Palace and the Hippodrome. The present building (now the Ayasofya Müzesi) built by Emperor Justinian I tmon during the first half of the sixth century and is the third church of Hagia Sophia was built here. The first church of the second half of the fourth century, known simply as the Great Church, and the second temple of the 5th century and destroyed by fire two, during a stopover in Istanbul.
The destruction of the Theodosian church during the Nika Stopping the 532 was a great opportunity for Justinian to build a church that will reach all the ecclesiastical buildings not only the city but throughout the Roman and Byzantine world.
As engineers appointed by Anthemius of Tralles and Isidore of Miletus. The construction proceeded rapidly and the new church, a huge domed basilica with an apse to the east and a total length of about 135 m, was inaugurated on 27 December 537. The bold construction of the first dome and the fact that the church was built in haste led to the collapse after the earthquake of 557. Unfortunately, there Procopius describes in detail the original dome. On the other hand, it is clear from the description of the property for re-erection of the temple that the dome was originally wider and lower than the second, built by the New Isidore, nephew of the first architect. The church opened again in 562.
The dome of St. Sophia is slightly lower than that of the Pantheon in Rome, and its diameter reaches 31.87 m and at a height of 55.6 m from floor level.
The innovative design of Hagia Sophia combines information already obtained in early Byzantine religious architecture (the Church of Saints Sergius and Bacchus, and perhaps to St. Polyeuktos), but in an original way and a much larger scale. The weight of the dome is distributed through the pendentives to four strong pillars. Among the developed four large arches, on which the dome seems to float, and of which the east and west end in semi-dome carried on smaller arched niches.
The central core of the domed church surrounded by aisles on the north and south side and a double narthex to the west. The galleries over the aisles and the inner narthex was accessed via spiral ramps at the four corners of the temple. Today only the northwest corner is used for this purpose.