abacus-like art piece at the D.C. Convention Center. I believe some of the balls are also racquetballs. There were three of these on the same wall w/the balls painted in different colors and arranged in different ways. When I first saw them, I thought, “cool, interactive art! They should have put them lower so little kids could play with them easier.” But when I went to play with them, I found they weren't interactive at all; the balls don't move. Too bad.