My favourite books are the trilogy about Arn,
http://en.wikipedia.org/wiki/The_Road_to_Jerusalem
http://en.wikipedia.org/wiki/The_Knight_Templar
http://en.wikipedia.org/wiki/The_Kingdo ... f_the_Road
http://en.wikipedia.org/wiki/The_Heritage_of_Arn
They describe life in medieval Sweden, knighthood, medieval battle tactics.
The third book is the best, which is about the main character building up defences, building castles and training cavalry. The books was the factor that brought me out of the dark age. I recommend them.
There has come a movie of the first two books now, but one should read the books first.