Motte and Bailey castles where built on hills with a wooden wall around them.The Motte is the castle on top of the hill
and the Bailey is the town underneath. The reason for this is so that the castle has control over the town underneath and
so that attackers have to attack a walled town and then climb a hill to take over the castle, so Motte and Bailey castles
were what William the Conquerer used to take over England from 1066 onwards.