This book has probably been mentioned before in other posts but I will repeat it here. I highly recommend The Kremlin and its Treasures, written by Irina Rodimzeva, Nikolai Rachmanov and Alfons Raismann. It was published by 1986 and 1987. ISBN: 0-8478-0856-4.
It contains some wonderful full color pictures of the grand halls, the state parade apartments, the private apartments, the churches, the treasures, the Terem palace, the Senate building and the general Kremlin area. It also had a very readable text.