The Fatih mosque complex was a religious and social building of unprecedented size and complexity built in Istanbul between 1463-1470 by the order of Fatih Sultan Mehmed. The mosque was built on the site of the former Byzantine Church of the Holy Apostles, which had been in poor condition since the Fourth Crusade, and was demolished in order for the Fatih mosque to be constructed. The Church was the burial place of the Roman Emperor Constantine — prior to the construction of the mosque, Constantine's sarcophagus was placed in the center of 12 sarchophagi representing the 12 apostles, in "the symbolic place of Christ.