"See you when I get home from Baghdad."

That's what it says on the rock placed on this headstone. It's a haunting message hidden among the 30,000 veterans from all of America's wars buried in Arlington National Cemetery. It's meaning sits heavy over the empty fields at the bottom of the cemetery, which will also one day be filled with rows of white headstones.

It's impossible not to be moved by a visit to Arlington National Cemetery, regardless of your views of war. Look past the famous headstones and memorials and you see that throughout the course of history, people from all walks of life have given their lives for something that they once believed in, among them more than 3800 former slaves who fought in the Civil War.

The Tomb of the Unknowns, at the top of the cemetery, is guarded by the U.S. Army 24 hours a day, 365 days a year. The 3rd U.S. Infantry (The Old Guard) began guarding the Tomb on April 6, 1948 and not a single day has passed unguarded since then.

Every half an hour in summer (and every hour in winter) you can watch the changing of the guards at the Tomb of the Unkowns