Between 330 and 336: Constantinian church of Hagia Eirene (the first cathedral of Constantinople).
c. 336: Central plan martyrium of the Holy Apostles and mausoleum of Constantine the Great
under Constantius II (337-361): Cross-shaped church of the Holy Apostles.
360: Consecration of the Great Church (the first church of Hagia Sophia, under Constantius II).
404: Destruction of the Great Church by fire.
415: Consecration of the Theodosian church of Hagia Sophia.
c. 425: Notitia urbis constantinopolitanae mentions 14 churches in Constantinople.
middle of the 5th century: Theotokos of Chalcoprateia (foundation of Pulcheria).
c. 454/463: Stoudios basilica (by senator John Stoudios).
463: Foundation of the Monastery of Akoimetoi, the katholikon of which became the Stoudios basilica.
518/9: Basilica of Sts. Peter and Paul (Justinianic).
527: St. Polyeuktos (foundation of Justinian’s political rival, Anicia Juliana).
536: Sts Sergios and Bakchos (Justinianic).
532: Nika Riot. Destruction by fire of the churches of Hagia Eirene and Hagia Sophia.
until 537: Justinianic church of Hagia Eirene.
27 December 537: Consecration of the Justinianic church of Hagia Sophia
536-550 (June 28): Justinianic church of the Holy Apostles. The mausoleum of Constantine was preserved, whereas a cross-shaped mausoleum is added on the NE corner for Justinian.
558: Collapse of the original dome of Hagia Sophia.
558-563: Reconstruction of the fallen dome with higher proportions and some changes on the base.564: Repairs on the church of Hagia Eirene that had suffered damages by fire.