A time travelers guide to medieval England by Ian Mortimer is a great book. I love all things medieval so if there are other books out there pertaining to all things medieval or renaissance please write back and let me know.
I also have the book by the same author, "The Time Travellers Guide to Elizabethan England." I haven't read it yet, but I did read the same one as you did and loved it.
There is a novel, The Doomsday Book by Connie Willis, about the Black Plague in the 1400's. Loved, loved, loved it. Also, I read Year of Wonders, by a different author, also about the plague. Pretty good, too.
Thanks Lady Renee for the book suggestions . The black plague has always intrigued me so on my next visit to B&N I will see if they have the books you mentioned. Life in a medieval castle by Frances Gies was pretty good. I love castles too so anything on them is great.