INSIDE THE HAGIA SOPHIA. The Hagia Sophia was the world’s largest church for nearly a thousand years, and the grandeur of its interior matched that of its exterior. Its plan is unique; it combines elements of a basilica and a square church. From the outside it looks almost square, but from the inside its structure—vaults, semidomes, and a central dome of more than 100 feet—causes it to feel rectangular. Detailed frescoes and mosaics covered its walls. These include winged angels on the corners of the central dome (pictured here) and a panel of Christ Pantocrater (“ruler of all”) flanked by his mother Mary and John the Baptist. During the Ottoman period, these were covered, and large calligraphic roundels with the names of Allah, Muhammad, and other notable Muslim figures came to dominate the decoration.