The LP says it's Istanbul's most famous monument. Guess so. Built by Emperor Justinian as an effort to restore the greatness of the Roman Empire. Finished it up in 537 and it lasted as a church til 1453 when Mehmet said uh uh and converted it to a mosque. It's been a museum since 1935 when Ataturk made it into a museum. UNESCO is paying for part of the current renovation.