Travel to the heart of St. Louis, Missouri and you’ll find the City Museum, possibly the best kids’ (and big kids’) playground in the world. Built on the 600,000 square foot site of the ex International Shoe Company, the museum/enormous jungle gym was constructed using unique, found objects from the city, and was dreamt up by artist Bob Cassilly. The result of the eclectic collection of objects is a gigantic playground with tunnels and slides, a ball pool, underground caves, a ferris wheel, old bridges, not one but two abandoned planes, and so many more fun features. The best thing about the City Museum is that it’s a constant work in progress and an enormous recycling project, always being updated and improved by a group of artists called the Cassilly Crew. See some pictures of the amazing park below.