Piranesi: The Complete Etchings
I bought this on a whim when I saw the price dropped to $20. Kudos for the completeness and, if all you want is a classical architecture reference book, this book will cover that. But, if you are interested in Piranesi the printmaker and his technique, this is pretty useless. The book is tiny. All the delicate line detail is invisible. The average plate is about the size of a business card with two or three images on each page. Ridiculous.