And worth every penny of admission. This museum is huge (400,000+ sq. ft.), has lots of permanent hands-on exhibits, and features many traveling exhibits as well (Mr. Rogers Neighborhood, Japanese Music, Moneyville, etc.). In 2004 they opened a new permanent exhibit - Dinosphere - that is incredible. They also have a special area for kids under 5 called Playscape.
Any time we have visitors from out of town, we always head to TCM - it's a guaranteed good time.