ARLINGTON, Va. (AP) — Hundreds of volunteers helped beautify Arlington National Cemetery at an event organized by a landscaping association.

The National Association of Landscape Professionals held its 21st annual volunteer day Monday at the cemetery. It's called Renewal and Remembrance.

More than 400 landscapers participated in the event, working to keep the cemetery looking good.

Arlington National Cemetery is more than 150 years old. It is managed by the Army, which first used the ground during the Civil War to bury dead soldiers. More than 400,000 are now interred there.