360: consecration of the Great Church in the reign of Constantius II
404: church damaged by fire during the riot that followed the banishment of the patriarch John Chrysostomos
415: consecration of Theodosius II´s Hagia Sophia
532: cathedral burnt during the Nika Riot
537: inauguration of the new domed basilica built by Justinian I
558: the dome collapses, after the earthquake of 557
562: second consecration of the Justinianic church
565-577: works on the patriarchal palace under the patriarch John III Scholasticus
667-669: Thomaites Hall added to the Patriarchate under Thomas II (or maybe under Thomas I, 607-610)
8th c: mosaics of Christ and saints damaged during Iconoclasm
790: Thomaites Hall damaged by fire and then reconstructed
later years of Michael III´s reign (r. 842-867): beginning of the re-decoration of Hagia Sophia with figurative mosaics - the Virgin Mary with Child Christ and the Archangel Gabriel in the apse
after 869: [reign of Basil I (867-886)]: further mosaics added and the west semi-dome restored after the earthquake of 869 (perhaps the four flying buttresses on the west facade of the church also erected at that time)
10th c: new mosaics: Leo I (886-912) above the door leading from the inner narthex into the nave; Alexander (912-913) portrait on the north gallery and the Virgin Mary with Constantine and Justinian I in the south-west porch
989: dome damaged by the earthquake; repairs by the Armenian architect Trdat (work finished in 994)
1042 -1055: mosaic of Christ enthroned between the Emperor Constantine IX (1042-1055) and the Empress Zoe in the south gallery
under John II Comnenοs (1118-1143): mosaic of the Emperor and his wife Irene flanking the Mother of God with Child Christ (on a side panel their son Alexios) in the south gallery
1203: Thomaites Hall burnt in the geart fire preceding the capture of the city by the crusaders
1204: cathedral spoliated by the crusaders; Baldwin crowned emperor in Hagia Sophia
1205: Hagia Sophia becomes seat of the Latin patriarchate
1261: the Byzantines recapture Constantinople; Hagia Sophia equipped with a new liturgical furnishing (Deesis mosaic in the south gallery dates in the late 13th- or early 14th c)
1317: massive outer buttresses on the east side of the church; some of those on the south and north sides erected by the Emperor Andronicus II (1282-1328)
1346: part of the dome, eastern main arch and semi-dome collapse
1353: repairs of the damaged vaulting of the church finished by the stratopedarches Astras and Giovanni Peralta; re-decoration of the dome with the Pantocrator mosaic
1453: fall of Constantinople to the Ottoman Turks; Hagia Sophia converted into a mosque by the Sultan Mehmet II (1421-1481); a medrese (religious school) erected near the mosque
before 1481: first (provisional) minaret erected on the top of a small staircase tower on the south-west corner of Hagia Sophia
Beyazit II (1481-1512): two minarets built, one of them damaged by the earthquake of 1509
1573: beginning of the reconstruction works by the architect Sinan; old minarets demolished and replaced by two new ones
1576: first of the sultan´s mausolea to the south of the mosque finished for Selim II
under Murad III (1574-1595): two minarets added
1618: Byzantine baptistery near the south-west porch of the mosque re-used as a mausoleum of the Sultan Mustafa I
under Ibrahim (1640-1648): ablution fountains built on the south-west corner of the mosque
1717: much of what remained from the Byzantine mosaics inside Hagia Sophia was covered
1738: library of Mahmut I built on the south side of the mosque
1739: şadirvan (fountain) erected in the south-west corner of the mosque precint
1743: imaret (soup kitchen) built north of the mosque
1754, 1766 and 1802: Ayasofya mosque damaged by earthquakes
1847-1849: complex reconstruction of the building by the Swiss architects Gaspare and Guiseppe Fossati in the reign of Abdülmecid – Byzantine mosaics were uncovered and recorded before covered again with plaster; exterior painted with stripes simulating the alternation of brick and stone bands usual in Byzantine structures; building of the muvakkithane (lodging for a time- keeper at a mosque) and the new medrese; the first thorough architectural survey of Hagia Sophia by W. Salzenberg
1873: demolition of the last standing parts of the Justinianic atrium
1931: beginning of a systematic uncovering and restoration of the mosaics by the Byzantine Institute of America
1934-1935: Ayasofya mosque secularized; becomes a museum
1935: excavations in front of the west facade of Hagia Sophia by A.M. Schneider lead to the discovery of Theodosius II´s propyleum and remains of the Justinianic atrium
1943: marble baptismal font found in the court between the Baptistery and the south aisle of Hagia Sophia
1980s: clearing of the Skeuophylakion and limited excavations immediatelly north of the north outer buttress of Hagia Sophia
1992-1999: restoration of the dome mosaics (project supported by UNESCO)
1993-late 1990s: removal of the modern exterior plaster on the south-west corner and partially also on the east facade
2000: restoration of the dome mosaics (project supported by World Monuments Fund)
2005-2007: restoration of the sultans' mausolea as well as of the Baptistery)