There are many preceeding five-star reviews for this product, all well-earned by an excellent company that is providing important research and background material to GM's who want to create real atmosphere for their players. I bought this entire series (Castles and Communities both) and am quite happy with it. Definitely read my fellow gamers' reviews to get more dirt on the details. I'll just say briefly:

This particular supplement is one of the finest I've seen; kudos for the excellent treatment of different kinds of structures, their placement and purpose as well as historic and cultural connotations connected with these structures. Furthermore, everything is presented so that the GM can digest it and implement it in her or his game without reading for hours. These folks are quite good at distilling what they're bringing to you without watering it down.