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.
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.