It took between 300 and 400 volunteers to help Danish artist Thomas Dambo realize Alexa’s Elixir, the “biggest and most ambitious exhibition” of his decades-long career. It features five giant trolls, a golden rabbit, three magic portals, and some 800 birdhouses scattered around the Detroit Lakes region of central Minnesota and just over the border in Fargo, North Dakota. Springing to life last summer, the fantastical creations—like everything the graffiti artist turned sculptor dreams up—are made of scrap wood and other recycled materials. Though Dambo has built installations all over the world and plans to put trolls in every U.S. state, something about this sylvan corner of Minnesota inspired him to go all out. “There were lakes everywhere!” says Dambo, who, along with his wife, scouted locations with 5-month-old twins strapped to their chests a year before the project began. He was particularly enchanted by the wildlife in the area. “We saw deer, turtles, and an eagle,” he says. “It felt like a fairytale.” Alexa’s Elixir includes the 432-foot-high Long Leif, the tallest troll Dambo has ever made, and a paunchy bunny fashioned from thousands of plastic bins upcycled from a Minnesota tool manufacturer. The locations of the completed artworks are kept secret so sightseers have to solve riddles to find them—or shortcut the whimsy by looking them up on Dambo’s comprehensive troll map—and geotag them for others to discover. To date, an estimated 6 million people have visited his trash sculptures around the globe—a stat that still floors the self-described garbage artist. “We have all this trash that’s suffocating the world,” he says, “but it also has the power to draw people out. The more people I can bring into this project—as volunteers or as visitors—the better I can explain why recycling is so important.”