One thing that fascinates me is how much of Byzantium survives despite earthquakes, wars and invasions. The Theodosian Walls alone are stunning, but scattered through Istanbul are small shrines, remains of buildings.

In Thessaloniki the effect is stronger still. Roman ruins seem to be all over -- one hotel had a good-sized excavation in progress before it! But the churches are all early Roman Christian.

Ephesus too has a lot of earthquake-ruined monuments.