A 17th-century fort was a military stronghold built to protect territories from invasions and attacks. These forts were often constructed using stone, brick, or earthworks and featured thick walls, bastions, and moats. They served as bases for soldiers and storage for weapons and supplies, playing a crucial role in conflicts during this period. Many 17th-century forts were strategically located near coastlines or trade routes to defend against naval threats and rival powers. Notable examples include the Fort Saint Elmo in Malta and Fortress of Louisbourg in Canada. These structures reflect the military architecture and tactics of their time.