[MC]
Round or sub-circular stone structure constructed on top of an earthen mound or motte at the focus of a more extensive defensive system that provides a fortified residence and military stronghold. Built in northern Europe from the mid 13th century ad onwards, many replaced earlier motte and bailey castles. The shell keep is typically 15m to 25m in diameter with thick walls and perhaps a single tower. Adjoining the keep will be one or more baileys providing an outer defensive circuit and accommodation for troops and servants. One of the best examples in England is Windsor Castle, Berkshire.
