The Apollo command and service modules were built at North American Aviation's plant at Downey, California. The lunar lander, in the eyes of some observers, was the most critical part of the Apollo vehicle. The many things that could doom the crew made ground-testing all the more important, so the company built a 150-foot-high Impact Test Facility. It looked like a gigantic playground swing and checked the module's structural integrity and impact loads by drop-testing it on water (shown here), sand, gravel and boulders.