Changing of the Guard at Arlington

This is the shift commander that is inspecting the "relief" soldier that will guard the tomb for the next hour.
Here is the soldier who is currently on duty. They undergo a synchronized pattern that is followed in steps of twenty-one for the entire hour they are on duty.
Here is the tomb of the unknown soldier that these men are guarding.

The commander with the two Army guards.

The commander inspecting the relief soldier to make sure everything is in order from his uniform to his gun.