Fort Belvoir is a United States Army installation and a census-designated place (CDP) in Fairfax County, Virginia, United States. Originally, it was the site of the Belvoir plantation. Today, Fort Belvoir is home to a number of important United States military organizations. The population of Fort Belvoir was 7,100 at the 2010 census.
The base was founded during World War I as Camp A. A. Humphreys, named for Andrew A. Humphreys. The post was renamed Fort Belvoir in the 1930s in recognition of the Belvoir plantation that once occupied the site, but the adjacent United States Army Corps of Engineers Humphreys Engineer Center retains part of the original namesake.
Fort Belvoir was initially the home of the Army Engineer School prior to its relocation in the 1980s to Fort Leonard Wood, in Missouri. It was also the home of the United States Army Engineer Research and Development Laboratory.
As a result of the 2005 Base Realignment and Closure Commission, Fort Belvoir had a substantial increase in the number of people stationed or employed there. All major Washington, DC-area National Geospatial-Intelligence Agency (NGA) facilities, including those in Bethesda, MD; Reston, VA; and Washington, DC were consolidated at a new facility, the NGA Campus East, situated on the former Engineer Proving Ground site. The cost of the new center was $2.4 billion.