In 2004 a creative Argentinean artist, Leandro Erlich, built a fake swimming pool that looks real from the top. He suspended a 10cm layer of water over a transparent glass on the top, while beneath the glass the room is empty. The walls are also carefully designed to give a original look of a swimming pool. Currently these fake pools are installed at PS1 Art Center in New York and the 21st Century Art Museum in Kanazawa, Japan. You can see more works from the same artist here.