MiniArt has produced some of the finest 1/72 scale building in injected plastic. They has a modular industrial brick buildings line which we reviewed in this article time ago, they can be combined with not much effort, parts are well engineered and casted and line is useful for a wide period, specially both world wars.

They also produce a good pair of medieval fortress by an affordable price, that again has some sort of modularity and you can combine several kits to make bigger fortress.

To finish they produced long ago (but still available) several east europe type barns, also useful for a very wide period.