It is a very thorough architectural dictionary, with good illustrations. It's Anglo-centric, and while some terms are slightly different, architectural jargon is pretty universal around the English-speaking world. The funny thing about architectural dictionaries as a professional is, if I have to look the term up, there's a good chance the person I'm talking to isn't familiar with the term either, so I'm better off just explaining what I mean in simpler terms.

Good find, Bill. I'll be bookmarking it.