9 Most Beautiful Buildings in the World, According to Architects

Hagia Sophia

Hagia Sophia was the cathedral of the Patriarchate of Constantinople, then a mosque, now a museum in Istanbul, Turkey. The church was built by Constantine the Great in 325 but burned down in a fire in 404. Rebuilt by Theodosius II in 415, the church was again burned down during the Nika Rebellion in 532. Nevertheless, it has received its final form in 537.