I'm sure these books must have been mentioned before, but they need to be mentioned again. David Macaulay has an incredible series of books showing how things like medieval cathedrals, castles, towns, and more were built. The books are aimed at children, but any adult would love them. The explanations are simple, the drawings are delightful. I highly recommend them to people going to Europe. We always wonder how pre-industrial populations were able to build amazingly complex (and huge) structures without modern tools; the answer lies in these books! I just found out that in addition to "Cathedral," "Castle," and "Town," he has "Mill" and "Mosque." I'm off to the library now!