At the end of my visit to Morocco last January, I had to spent quite a few hours at the small Marrakech airport due to a delayed flight. They have a small bookshop in the departure area, and that's where I enjoyed browsing several books on Islamic architecture.
I did not make a choice then, but at home I ordered this one at Amazon: Islam: Art and Architecture by Markus Hattstein (Author, Editor), Peter Delius (Editor)
The subject is mainly Architecture. It has 600 pages, very good photography (showing the monuments from different angles) and a good outline of the history of the main islamic empires of the past. Lots of WHS are highlighted, in Iran, Uzbekistan, Syria, Egypt, Morocco etc, with a lot more info and context provided than in general books on WHS.
So, I was really happy with this purchase and can recommend it to anyone interested in history and architecture.