Blockhouse #13 was a small two story structure, also referred to as a safe house, that was common in early settlements for protection against attacks from Native American tribes. Many early settlements transitioned into forts, which were not always military. In a fort enclosed by a palisade wall, blockhouses stood on all corners and were built to extend outward from the palisades so there was a clear line of sight from one blockhouse to another along the exterior perimeter. The upper level of a blockhouse always overhangs the lower floor, allowing soldiers or settlers above to peer downward through gun portals. If attackers got against the lower building wall beneath the lower gun portals, the manned upper floor became the eyes for those below.