Recently purchased this book off of the internet from the Expeditious Retreat Press (www.exp.citymax.com
). 144 pages, based on the D20 system, and good material for GMs, and for medieval readers. The book details medieval life in a Dungeons and Dragons setting (using popular spells in how they would affect the average medieval citizen. Manor, town, and kingdom generator as well as some really thorough information on construction (costs, expansion, types of material, cartage of building materials, that sorta thing.)
I like the book, but it is $25 and not for everyone. If words like demographics and economics scare you, the book isnt for you. If you do think about how long it would take to built an ornate cathedral or a fortress and surrounding villages for support, then this is a top notch piece of work.
Personal note, when I ordered the book, I flubbed up on the process and actually ordered two copies. I was quickly contacted over the matter to insure that I wanted one copy and had problems or if I wanted two books rather than the one. The matter was handled quickly, and I was happy with the transaction.