Hagia Sophia’s rebuilt dome was completed in 562 after the first dome collapsed.
The church commissioned by Emperor Justinian I was dedicated in 537. Its original dome was unusually broad and relatively shallow, and part of it collapsed after an earthquake in 558. The architect Isidore the Younger supervised a reconstruction that raised and strengthened the dome.
The rebuilt structure was rededicated in 562. Later earthquakes caused further damage and repairs, so the dome seen today is the result of many historical interventions rather than a completely untouched sixth-century surface.
The date 537 remains important because it marks the completion of Justinian’s present church, while 562 refers specifically to the post-earthquake rebuilding. Confusing these dates is a common mistake when tracing Hagia Sophia’s construction history.