The Pentagon The Pentagon The Pentagon, in Arlington County, Virginia, across the Potomac River from Washington, D.C., is the headquarters of the United States Department of Defense. As a symbol of the U.S. military, the phrase "The Pentagon" is often used as a metonym for the Department of Defense and its leadership. The building was designed by American architect George Bergstrom and built by contractor John McShain. Ground was broken on September 11, 1941, and the building was dedicated on January 15, 1943. General Brehon Somervell provided the major motivating power behind the project; Colonel Leslie Groves was responsible for overseeing the
Arlington County, Virginia 2018 ParkScore ranking of the top 100 park systems across the United States, according to the ranking methodologies of the nonpartisan Trust for Public Land. The climate in this area is characterized by hot, humid summers and generally mild to cool winters. According to the Köppen Climate Classification system, Arlington County has a humid subtropical climate, abbreviated "Cfa" on climate maps. As of the 2010 census, there were: The population density was 8,309 people per square mile (2,828/km²), the highest of any county in Virginia. According to the US Census, the racial makeup of the county in 2012 was: There