Hagia Sophia was a revolutionary building considering the early church architecture. Roman churches were modeled after the Basilica, an ancient Roman structure. There would be no flashy domes in these structures.

Hagia Sophia was the first Roman church to have a giant round dome. It was only during the Renaissance that domes of this size were built in Europe. Hagia Sophia had achieved this 1000 years ahead. Therefore, Hagia Sophia is very important in world architectural history.