On Mount Rutsen an old stone observation tower was built by the Astors.[2] A second tower was built for the United States Coast and Geodetic Survey to help with map-making. Finally, the second tower was built during World War II by the United States Army Corps of Engineers as a watch tower.[3] This enclosed tower contained a telephone as well as utilities for full-time occupation[2] so that enemy planes could be spotted. This tower was particularly useful in watching out for planes attempting to attack President Roosevelt's home and those approaching New York City.[3] After the war, the tower became a popular attraction and was purely recreational.[2] In 2006, the tower was deemed unsafe and was replaced in 2007 by the current observation tower.[3]