Some of the most popular tourist destinations in world are ancient forts, castles, and battlefields. It is fun to imagine what it was like to live during a time when people fought with swords, cannons, muskets, and bows. In the Middle Ages, leaders constructed massive fortifications to protect their people. Forts and castles signified power, wealth, and military capability. Some of the greatest minds in the history of warfare designed fortresses to withstand any attack.