Intertwining tree branches, dark damp caves and a metal jungle of scrap parts, including a school bus and two airplanes, take shape at St. Louis’ City Museum to create a playground that can be intimidating to an adult visitor, especially with hundreds of youngsters scurrying through tiny passageways and climbing like chimps high above the city streets.

The City Museum, a vision of the internationally acclaimed sculptor Bob Cassilly, was built in 1997. Cassilly and his crew create the attractions in the museum from reclaimed building materials no further than the city’s municipal borders and donated souvenirs. The City Museum now is opening the minds of approximately 2,200 visitors daily.

A recent trip to St. Louis to talk to a group of students about the “alternative art movement” — I modestly cast myself as an emblematic figure in the transition from the artist-run nonprofit spaces of the 1970s through the ironically commercial East Village storefront gallery scene of the ‘80s to the all-out commercialism of today’s robust art market — provided a welcome opportunity for a quick survey of the local art scene.

What’s happening in St. Louis? Not a lot — my whirlwind tour was completed in a day and a half without too much trouble, and meter parking was readily available at every stop — which makes the place a welcome contrast to traffic-jammed New York.

Bob Cassilly built St. Louis’s City Museum from the very stuff of the city. Named for maximum generic effect, the museum is privately owned (half by Cassilly, who serves as creative director) and has no legal connection to local governance. But this mixture of children’s playground, funhouse, surrealist pavilion, and architectural marvel made of found objects has roots in the city deeper than any other institution’s.

“I leaped up and grabbed the guy by the beard,” recalls Bob Cassilly, now 48, who scrambled onto the Madonna‘s marble head to reach the disturbed Hungarian-born geologist, who was perched on a ledge. “We both fell into the crowd of screaming Italians. It was somewhat of a scene.”

Twenty-five years later, Cassilly is creating another ruckus—and scaling new heights—with the nonprofit City Museum he and his wife, Gail, have opened in downtown St. Louis: a fantasia of Cassilly’s own giant animal sculptures, stone trees and caves. Climbing is not only welcome, it’s encouraged (but leave the hammers at home). Since he sold his first public sculpture in 1989, Cassilly’s reputation has grown as rapidly as his work, which ranges from life-size (the hippo fountain in New York City’s Central Park) to fright-size (a 67-foot bronze giraffe at the Dallas Zoo).