Just my thread for interesting stuff.
Principality of Theodoro.
https://en.wikipedia.org/wiki/Principality_of_Theodoro
http://www.graal.org.ua/en/theodoro-principality/history-of-theodoro
http://whc.unesco.org/en/tentativelists/5773/
Mostly interested because here survive traditions of Ancient world city building, quite different from tight and non-ecological "European" (after fall of Roman Empire) city building.
Capital of Theodoro is Mangup Kale.
http://en.wikipedia.org/wiki/Mangup
Other example of Byzantian city is Chersonesus.
https://en.wikipedia.org/wiki/Chersonesus