Deborah Dwork & Robert Jan Van Pelt, "Auschwitz" (1996)

This book is well-written, meticulously researched, chock full of singular illustrations (rare photos of the town of Oswiecim, maps, and design drafts of camp buildings) often drawn from the authors' personal collections, and takes a surprising breadth of approach (considering the development of the Auschwitz-Birkenau concentration camp complex within the 1,000-year history of German colonizing drives towards the East as well as anti-Semitism). In short, this is a really excellent book.

The BBC produced a great documentary, Auschwitz: Inside the Nazi State based on some of the research for this book. The PBS-linked site contains much of the same maps, blueprints, and other materials contained in the book.