Construction of the Hagia Sophia in Constantinople is finished. Construction started on February 23, 532, on orders from Emperor Justinian I to replace an earlier church which burned down during revolts in the city. This is the third basilica to be built on this site and Justinian has material from all over the Empire used.
At the time of its completion this Hagia Sophia is the largest building in the world and helps redefine Byzantine architecture. It will remain the largest cathedral in the world for almost 1,000 years, and it will be the Greek Patriarchal cathedral of Constantinople until 1453, when Constantinople is conquered by the Ottoman Turks.
Under Turkish rule the Hagia Sophia is turned into a mosque and remains that way until 1931, when it is secularized by the new Turkish government. In 1935 it reopens as a museum.