I can think of a few places:
Mayan / Aztec civilisation
Feudal Japan
Ancient China
Ancient Egypt
Victorian London
French Revolution
Roman Empire
Ancient Greece
Ancient India
Edit: or an open world (AC4 style) with medieval Europe. France, England, Spain, Netherlands... the variety, architecture, atmosphere, etc. would be fucking amazing.
No troll is too much for me to handle. I rehabilitate trolls, I train people. I am the Troll Whisperer.