There is a monument at Arlington National Cemetary dedicated to the Unknown Soldier.  It is for the soliders whose remains were not able to be identified.  They are still soliders who fought for our freedom and guarding their tomb is one of the highest honors. The guardians are called Sentinels and when they are chosen to serve, their duty lasts for the rest of their lives.

Fewer than 20% of the volunteers who sign up to become Sentinels are actually chosen to serve at The Tomb Of The Unknowns.  They are called the Third United States Infantry or "The Old Guard" Those who are chosen then commit to guard the tomb on a rotation that lasts for two years.  The guard is changed every 30 minutes, 24 hours a day, 365 days a year.

However, after their two years is up, the duty doesn't end there.  They offer to refrain from drinking alcohol (on and off duty) for the rest of their lives.  They cannot swear in public FOR THE REST OF THEIR LIVES and cannot do anything that would disgrace the uniform or the tomb in any way.

The precision of the guard is amazing.  The 21 steps that they take as they "walk the mat" have worn a path not only on the mat but on the concrete that is walked every day.

I have to admit that I have never seen it in real life but from the videos I've seen of the changing of the guard, it is one of the most precise, well timed, motions I have ever seen.  Every step is counted and every detail is accounted for.  From the inspection of the weapon, to the way that the solider is groomed, nothing is overlooked.

Here Rests In Honored Glory An American Soldier Known But To God

Even the mood of the tomb must remain somber to remember the incredible sacrifice that these men and women have made for us.  As seen in this video, you can see a soldier who reprimands some tourists who have obviously forgotten why they are all there.

For more interesting facts about The Tomb Of The Unknown Soldier, check out this page.