The NAAMHC became the deepest museum on the National Mall. Excavators dug below grade to lay the foundations, although the building itself will be only deep. The museum is located at a low point on the Mall, and groundwater puts on the walls. To compensate, per minute of water were pumped out every day during construction of the foundation and below-grade walls, and a slurry of cement and sand injected into forms to stabilize the site. Lasers continually monitored the walls during construction for any signs of bulging or movement.