A castle is a type of fortified structure built in the Middle Ages. Castles were typically built for defensive purposes and served as residences for royalty and nobility. The architecture of castles varied depending on the region and the time period in which they were built. Some castles were built with stone walls and towers, while others were constructed with wood and earthworks. Castles played a significant role in history, serving as centers of power and control. Today, many castles have been preserved and are popular tourist destinations, offering a glimpse into the past and its architectural achievements.