Cascading down the Don River ravine, this sizable complex takes full advantage of its natural site. Raymond Moriyama designed a series of concrete and glass buildings on different levels connected by enclosed escalators. Opened in 1969, this popular attraction consists largely of interactive exhibits on science and technology. Visitors learn, for example, by pushing buttons, rotating cranks, pedalling bicycles and turning wheels. Chemistry, printing, electricity and paper-making demonstrations, to name a few, provide other means of education. The five levels are designated by letters, levels B, C, D and E being the exhibit/activity floors. Level C's Earth/Food section has a 5m/15ft-high stack of grocery-filled shopping carts to illustrate "Food for a Year," while Space includes a rocket chair, hydroponics, supergravity and other exhibits. Highlights of level D are the Living Earth exhibit, where visitors explore a limestone cave and experience an indoor rain forest; the Hall of Transportation, with its ascending model hot-air balloon, CA-3 powerboat and old-fashioned bicycles; the Science Arcade, with humorous electricity demonstrations; and Communications, where visitors can participate in papermaking. The Hall of Technology features, among other displays, life-size and model cantilever bridges for observing the effects of stress, and most recently, an Information Highway exhibit where visitors can access the Internet.