The Hagia Sophia (Ayasofya) is arguably Istanbul's most important monument. Built in just 5 years (532–537 AD) by Byzantine Emperor Justinian I, it served as the world's largest cathedral for nearly 1,000 years. After the Ottoman conquest of 1453, it became a mosque, then a museum in 1934, and returned to mosque status in 2020. Its massive dome (31 meters in diameter, 55 meters high) was an architectural marvel that influenced building design for centuries.
Inside, magnificent Byzantine mosaics depicting Christ, the Virgin Mary, and saints coexist with Islamic calligraphy panels and Ottoman additions. Entry is free (as a functioning mosque) but visitors must dress modestly — scarves are provided for women at the entrance. Non-prayer visiting hours are between prayer times. Photography is allowed. The building's scale and beauty are overwhelming — allow at least 45 minutes to properly appreciate the interior.





