Here's some very cool castle pics from a few books which I own....(the sketch picture & info are worth printing out)
Almodovar Del Rio:
Almodovar Close up (more detail):
Castle Sketch (you guys will like this one):
Castle Sketch Info (this goes with the pic above):
The pics come from "Castles & Fortresses" by Robin S. Oggins.
The sketch pic & info come from "The Medieval Fortress" by J. F. Kaufmann & H. W. Kaufmann.
Both are very good books which I recommend!