This is the third church of this name to sit on this site and is oriented so that its apse faces sunrise at the time of the Winter Solstice. It is approximately 70m x 75m.
The first construction was completed in 360 but was burnt down in 404. A second was built by Theodosius II in 415.
The Emperor Justinian appointed Anthemus of Trailles and Isidore of Miletus to oversee the third construction and it was completed in 532. However the 48m x 32m atrium to its west has disappeared and is now covered by a garden. The shallow dome was weakened by the earthquakes of 553, 557 and 558 and it partially collapsed. It was replaced by a steeper dome to reduce the stresses and was reconsecrated in 563. A series of earthquakes in the 9th-10thC caused part of the dome to collapse, the effect of which was to include buttresses or piers on all sides of the exterior. Its interior suffered in 1204 when it was stripped and converted to a Catholic church before being reconsecrated in 1261. Another earthquake closed it between 1346-55 and it fell into disrepair in the last century of Byzantine rule. It was converted to a museum in 1934.
