A castle is a type of fortified structure built during the Middle Ages predominantly by the nobility or royalty and by military orders. Scholars debate the scope of the word castle, but usually consider it to be the private fortified residence of a lord or noble. Over hundreds of years, castle styles changed and evolved to include a moat, turrets, and complex wall systems. The three main types of castles used in the Middle Ages were the motte-and-bailey, stone keep, and concentric castles. Enable our skill and stay updated with the latest news , discoveries, tips and tricks. The information in this skill is provided for informational and educational purposes only.