http://www.castlesontheweb.com/
The ghosts on this site sometimes won't let you leave! http://www.nationalgeographic.com/castles/enter.html
http://www.pbs.org/wgbh/nova/lostempires/trebuchet/
http://scholar.chem.nyu.edu/
http://www.castles-of-britain.com/
http://www.learner.org/exhibits/middleages/
http://www.mrdowling.com/703middleages.html
http://www.learner.org/exhibits/middleages/feudal.html
http://www.georgetown.edu/labyrinth/
Knights and Armor http://historymedren.about.com/homework/historymedren/msubmenuknight.htm