Butterfly Wall by Charles Sowers at San Francisco Airport (SFO) in Terminal 2

Butterfly Wall consists of 20 hand-cranked mechanical butterflies that are propelled up a cable to gently flutter back down again in a delightful random choreography dictated by the air resistance of their spinning dichroic wings. When the cranks are not being used, a programed set of movements activates the butterflies.

ButterflyWall from Charles Sowers on Vimeo.

There is also a smaller version near the entrance at the Exploratorium in San Francisco.

http://charlessowers.com/