Arlington National Cemetery commemorates soldiers from every war the United States has fought since the American Revolution. It is the resting place for such notable American leaders as President John F. Kennedy, jurist Oliver Wendell Holmes, and civil rights activist Medgar Evers. The site of some 400,000 graves, the 624-acre (252-hectare) cemetery, set across the Potomac River from Washington DC, is visited by millions of people each year.