The Trulli houses of Alberobello in the Puglia region of Italy were built by settlers from limestone and not much else. An impressive dry stone building technique meant the houses could be collapsed simply by pulling out a keystone.
Ruins of Ephesus, Turkey. The library of Ephesus.one of the three great ancient libraries.including the one at Pergamum (also in Turkey) and Alexandria, of course in Egypt. There's a public restroom across the street.