This was ideal to survive since it is located on a steep hill.View attachment 615488
Blagaj Fortress (or Old Town of Blagaj), Bosnia and Herzegovina. It became the main safe zone in Mostar against zombies as it is well protected in a dangerous place for hordes, and had wells, weapons from the castle and military, near food sources, also that was being restored during the Great Panic.
Wikipedia says this of Blagaj Fortress:This was ideal to survive since it is located on a steep hill.
Irony how castles and forts are considered obsolete in modern warfare but against a human-wave enemy, it would hold out.
I'd say Neuschwanstein Castle survives just fine, but....it's located in southwest Bavaria alreadyBritain has lots of Castles, but so many are actual ruins that cannot be easily be made liveable even if easily refortified.
Having said that, a lot will depend on on time available before the Horde hit the Castles location and what starting state the place is in. Windsor will be a lot easier to fortify than say Dudley or Kenilworth.
I'd guess France and Spain with a similar history of Castles would be roughly the same. Eastern Europe seems to have a lot more intact fortifications- though those 'fairy tale' Castles in Germany are toast.