The Saint Louis Science Center is unusual for spanning Interstate 64 — a glass bridge runs over the highway with radar guns measuring the cars below for visitors to read off as a real-time physics exhibit. The main complex on the south side of Forest Park covers astronomy, ecology, paleontology, and the inevitable interactive sections aimed at children, plus a James S McDonnell Planetarium.
Admission to the main centre is free; the planetarium shows, OMNIMAX films, and special exhibitions cost extra. It is one of the few science centres in the country with no general admission charge, and the planetarium's modernist building, designed by Gyo Obata in 1963, is an architectural landmark in itself.