At the Pentagon Sept. 11th memorial there are hundreds of these benches. Each bench sort of looks like a wave and underneath of it is a pool of water. The water runs so you can hear the sounds of soft trickling water. I think that each bench represents up to three people. They are organized by age, thus when you first enter the vast space of the memorial you're greeted by a bench in honor of a baby. I took a lot of pics of the benches.