If an existing mound was not available it appears that the castle builders went to the trouble of building their own. If the motte was strong enough the wooden keep could have been replaced by a stone building. A stone keep offered much better protection from attack than a wooden keep that could easily be burnt down.

Usually the motte was cut off from the the bailey by its own ditch and could only be reached via a causeway or bridge. The bridge would have been designed to be defendable against attack and possibly retractable using a drawbridge. At times of attack the motte and keep were the last line of defence if the attackers managed to get into the bailey. The defenders could shoot arrows or throw rocks down at the attackers.

Some early castles had more than one motte. The castles at Lewes and Lincoln both have two mottes.

On top of the bank a palisade of wooden planks or logs was constructed to add extra height. A wall walk was usually built behind the palisage to allow the defenders to see over the top and fire missiles down on attackers below who were attempting the climb the bank. The palisade continued all the way around the edge of the bailey and its only real threat was from fire. This threat eventually lead to the introduction of stone for building material.