City Museum

City Museum in St. Louis, Missouri is one of the most unconventional attractions in the United States — part playground, part art installation, part architectural salvage project spread across a 600,000-square-foot former shoe factory. Founded by artist Bob Cassilly in 1997, the museum is constructed almost entirely from reclaimed materials: giant cement tubes, old construction cranes, school buses suspended five stories above the street, coiled airplane fuselages, vintage bridges, and miles of rebar tunnels woven through the building's exterior. Visitors crawl, climb, slide, and squeeze through an enormous outdoor structure called the Monstro City, which encases the building's facade and includes three-story tunnels open to the sky. Inside, the Enchanted Caves section offers tight crawl-through tunnels lit with LED lights, while the Museum of Mirth, Mystery & Mayhem occupies an entire floor of carnival oddities and taxidermy. The rooftop ($5 extra) holds a ferris wheel, a school bus hanging over the edge, and an additional slide network accessible only from above. Children thrive here, but adults — especially on Friday and Saturday evenings when the venue pivots to a 21-and-over atmosphere with a bar — find it equally captivating. There is no linear tour route: exploration is self-directed and the space rewards repeated visits. Wear clothes that can get dirty, expect to sweat, and plan for at least three to four hours. The venue is genuinely difficult to visit in under two hours without missing significant sections. Weekend afternoon crowds are heavy — Monday and Tuesday visits, when available, offer the most comfortable experience.