Multiverse (2008) by Leo Villareal in the Concourse between the East and West Buildings of the National Gallery of Art
If you want to walk from one of Washington, DC's National Gallery of Art Buildings to the other, you can either simply go outside or you can wander through the underground tunnel that connects them. There you will find a light display called Multiverse by Leo Villareal. You can watch it change as you go by and be surprised by its enigmatic glow. Then you will come upon another surprise, a large glass window in front of a waterfall.
Cascade Waterfall, National Gallery of Art Concourse, Washington, DC