If I look up from my tablet right now, I see out my window an old stone tower atop a small hill. This is Clifford's Tower. Between us is a street busy with cars, double decker busses, and pedestrians.

Clifford's Tower is the largest remaining part of York Castle. The castle was once the centre of government for the north of England. In the 11th century an earth mound was built and topped with a timber tower. In 1190 the tower was burned down after York's Jewish community, some 150 strong, was besieged here by a mob and committed mass suicide. The present 13th-century stone tower was thought to have been used as a treasury and later as a prison.

Today the tower is just a clover-shaped wall of stone. The corners protrude a bit for defensive purposes; the design affords better views of any attempts to scale the wall. Inside is a modern steel and wood structure that helps stabilize the walls and affords places for tourists to explore.