I think these are amazing!:

Philadelphia International Airport (PHL)

PHL has a highly regarded program of rotating art exhibits, as well as a permanent art collection that includes “Impulse.” Ralph Helmick and Stuart Schechter’s six hanging sculptural installations each contain more than 1,000 three-inch bird sculptures that, when seen from various distances, seem to transform from a disorganized flock of birds into the shape of a giant goose and then into a classic DC-3 aircraft. Seattle-Tacoma International Airport and Chicago’s Midway Airport have similar image-shifting sculptures.