When visiting a desert, you’d expect to see cactuses, tumbleweeds, and endless stretches of sand. But if you’re in the Mojave Desert, 10 miles south of Las Vegas, Nevada, you’ll see something strange: seven stacks of brightly colored boulders, each 28 to 35 feet high.

The towers, called the Seven Magic Mountains, are part of a two-year art installation that opened in May. Swiss artist Ugo Rondinone cut locally sourced limestone into 33 boulders of varying shapes and sizes and used a crane to lift and stack them. He then painted the boulders an assortment of nine fluorescent colors—using nearly 330 gallons of paint! The aim of the artwork, Rondinone says, is to compare and contrast nature with an artificial structure. His vibrant, Day-Glo totem-pole stacks are hard to miss in the flat, sandy desert.