The Frankish Tower at Acrocorinth was built in the 13th century following the Fourth Crusade, when the fortress became part of the Principality of Achaea under Crusader control. This square stone tower exemplifies Western European military architecture and served as a command post at the summit's highest point, providing unparalleled defensive views across the Peloponnese. The Franks maintained the site's strategic and spiritual importance, building churches within the fortress walls while strengthening its defenses against future sieges.