Towering over the Bosporus Strait, which separates Europe and Asia, the Hagia Sophia (Church of Holy Wisdom), reflects traditions from both continents. Built as a cathedral in the sixth century A.D. by Emperor Justinian I, it became the most important church in ancient Byzantium. Mosaics, marble pillars, and rich coverings mark the vast, dimly lit interior, though many mosaics were taken during the Crusades in 1204. The Ottoman Turks conquered Constantinople in 1453 and converted the building into a mosque, adding four minarets and, later, a religious school and mausoleum. In 1934 the Turkish government turned the structure into a museum, though its soaring dome continues to attract spiritual pilgrims.