deus-ex-machina said:
I know it's been hinted at with other suggestions but:
Abandoned mental asylum.
As someone else mentioned earlier, there's one in Thief : Deadly Shadows - the Shalebridge Cradle. An abandonded metal asylum and orphanage, all in one.
Coincidentally, there used to be a mental hospital not that far from where I live now, tucked away in amongst the trees behind an overgrown field. It was eventually vacated but they left the buildings there for many years thereafter. It was something of a rite of passage to go exploring that place in the dead of night. Alas, the whole site has been cleared out to make way for a shiny new housing estate, but such is the price of progress I guess. Though I still find myself half hoping that the restless spirits of former patients at the mental hospital will be disturbed and make life a misery for whoever moves into the new estate.
Also, schools can quite creepy late at night I think. That may be because when you go to school, you would very rarely there be there after all the pupils and staff have gone home. It would quite eerie to be stuck in an empty school building overnight. Especially a primary school, as little kids are so much scarier.
To reinforce the "Soviet" theme - I saw a good number of videos recorded inside the sarcophogus (sp?) in Chernobyl - those videos alway creep me out slightly.
An abandonded school/orphanage/mental asylum complex housed inside a concrete sarcophogus hidden in the middle of a dark forest though, that might just be too much....
