Chantilly is an unincorporated community located in western Fairfax County and southeastern Loudoun County of Northern Virginia. Recognized by the U.S. Census Bureau as a census designated place (CDP), the community population was 23,039 as of the 2010 census -- down from 41,041 in 2000, due to the splitting off of parts of it to form new CDP's including Greenbriar and Fair Lakes. It is named after an early 19th century mansion and farm.
Chantilly is part of the Washington metropolitan area and is approximately 24 miles (39 km) from Washington, D.C.
Chantilly is home to Washington Dulles International Airport, which serves Washington, D.C. It is also the location of the Steven F. Udvar-Hazy Center annex of the National Air & Space Museum and the headquarters of the National Reconnaissance Office.