Hagia Sophia

Justinian had it built in five years, completed in 537, and it remained the largest cathedral in the world for nearly a thousand years. Its thirty-one-metre dome rests on pendentives, a new structural solution that makes it seem to float — a ring of forty windows at its base helps.

It has been an Orthodox church, a Catholic cathedral after 1204, a mosque from 1453, a museum in 1935, and a mosque again in 2020. The Byzantine mosaics, covered over and then uncovered, sit alongside the Ottoman calligraphic medallions: that layering is what you come for.