If you’ve driven along I-25 near downtown Denver during the past few months, you’ve probably noticed mysterious-looking orbs emerging in front of the city’s ever-growing skyline. They aren’t UFOs (though the tallest one does provide an excellent view of the heavens). Rather, they’re part of the Children’s Museum of Denver at Marsico Campus’ new Adventure Forest, which is set to open June 3. The goal of the $2.3 million aerial obstacle course is to create a superplayground that inspires kids ages five and up—and adults—to engage in free-range play, a less structured, more inventive style of recreation that research says boosts physical dexterity and creativity. In practice, that means each stage of the 500-foot-long route will include beginner, intermediate, and expert challenges; your budding pathfinder can choose her own adventure, whether that’s taking a flight of stairs or climbing a rope net. Eventually, all routes lead to the giant orbs, where a lookout with a 360-degree vista of the mountains and the Mile High City might just be the course’s most inspiring feature.