Just north of Moab, Utah, Arches National Park is home to more than 2,000 natural sandstone arches – the densest concentration of arches in the world. Today's image, North Window, is one of the best-known formations in the park's Windows Section, where towering fins, openings and sculpted sandstone create a landscape that looks almost architectural.

North Window certainly has the look of a giant stone gateway, framing distant cliffs and ever-changing skies. But there was no blueprint, architect or construction crew involved. Instead, water, ice, temperature changes and gravity gradually wore away softer rock, leaving the tougher layers behind.