Hagia Sophia

Ἁγία Σοφία (Greek) / Ayasofya (Turkish):
the world's largest cathedral for almost a thousand years until the 16th century

537 - 1204 : Orthodox Patriarchal Cathedral
1204 - 1261 : Roman Catholic Cathedral 
1261 - 1453 : Orthodox Patriarchal Cathedral
1453 - 1931 : Ottoman Mosque
since 1935 : Museum