Throughout the middle ages castle construction evolved from Motte and Baily castles made of wood to Stone Keep castles made of stone to Concentric castles which utilized thick/tall stone walls built around the stone keep. Castle builders had to come up with new materials to use, new building techniques, new types of castles, and new castle features to withstand attacks by armies that were constantly developing new methods of attack and new weapons to use against castles. Go to this web site and play the Castle Under Attack simulation game! Click here: http://www.historyonthenet.com/Lessons/attackdefendcastle/mottebailey.htm
Parts of a castle: crenellations, merlons, and arrowloops.
Castle walls were built with defense in mind. Below are pictures showing crenellations and merlons along the top wall of a castle. Note the different shapes of arrowloops. Here is a link to a web site with information about crenellations: http://www.castles.me.uk/crenellations.htm
Arrowloops were typically wider on the inside of the wall and narrower on the outside.
Internal view of arrowloop.
