Iberia, for example.
Before or after the Muslim invasion?
I have seen and toured the castle in Poland, and driven past the Battle of Grunwald site. This is also some of the same area where Hitler had his Wolf's Lair (further north), which had been pretty run-down. At least it was run down when we beat the Soviets.
http://www.youtube.com/watch?v=MamuJHShRls