17. The Hagia Sophia Is a True Marvel
The Hagia Sophia was constructed during the reign of Emperor Justinian to replace buildings that had been destroyed in the incredibly violent Nika Riots. It is the pinnacle of Byzantine architecture and is widely heralded as a wonder of the era. The huge freestanding dome was said to be held up purely by the will of God. The building was repurposed as a mosque in the 14th century and is now a famous museum and tourist attraction.