Forts are fortified structures built to protect against enemy attacks. They often feature thick walls, towers, and moats, serving as military bases or safe havens for troops. Historically, forts were strategically located near borders or important trade routes to defend territories. Many forts were constructed during times of conflict, such as the American Civil War or the Roman Empire. Some famous examples include Fort Sumter in the United States and Fortress of Louisbourg in Canada. Today, many forts are preserved as historical sites, allowing visitors to learn about their significance and the history of military defense.