FSB Mary Ann's construction was no different from many other U.S. firebases in South Vietnam. Running northwest to southeast, the firebase stretched 500 meters along the crest of a ridge connecting two hillsides. Only 75 meters wide at its narrowest point, Mary Ann widened to 125 meters at the northwest and southeast ends. A trench, "knee-deep in certain stretches and waist-deep in others" defined the base's perimeter and connected the base's twenty-two bunkers. Like any typical late-war FSB, most of Mary Ann's bunkers were made from converted metal shipping containers known as conexes. In addition to the conex bunkers, Mary Ann had over thirty assorted structures (hootches, sandbagged bunkers, and other makeshift structures). The southeast end of FSB Mary Ann housed the Battalion Tactical Operations Center (B-TOC) and Company Command Post (CP), both located next to a small VIP helipad. The base's mess halls, a communication center, the Battalion aid station, ammunition bunkers, storage for general supplies, and two artillery firing positions were also located at this end of the FSB. The northwest end of the base housed a second artillery position with two 155mm howitzers, the fire direction center and the artillery command post. The saddle between the two ends of the FSB served as the resupply helipad. Dirt roads divided both ends of the base, and also ran outside the wire at two points: southwest past a firing range to the spring that served as the base's water point and northwest to the trash dump.