This rather battered-looking keep at the top of a steep mound is all that remains of the old York castle. Sitting on a grassy mound, this squat stone tower dates from the early 12th century. The Norman tower that preceded it, built in 1068 by William the Conqueror, was destroyed in 1190 when more than 150 Jews locked themselves inside to protect themselves from a violent mob. Trapped with no food or water, they committed mass suicide by setting their own prison aflame. From the top of the tower you have good views of the city.