I picked up some 15mm Russian Buildings from Minibits. They are very cheap, but turn out pretty good. I did the minimum with them and I like how they ended up. They can be used for pretty much any period (and theatre, really). There’s a few more pictures on my blog (including some other stuff), have a look here:
I used Vallejo’s Grey Green or Green Grey (I forget exactly which one) then washed them in a thin brown wash and drybrushed in Khaki, IIRC I then used Flory Washes to add some weathering in the form of streaks. They looked a bit dull until I added the green windows and doors.