Hagia Sophia (&quot;The Holy Wisdom of God&quot;) - Famous in particular for its massive dome, it is considered the epitome of Byzantine architecture and one of the most beautiful buildings in the world. It was the largest cathedral in the world for nearly a thousand years, until the completion of the medieval Seville Cathedral in 1520. Designed by Isidore of Miletus and Anthemius of Tralles.