Rainbow Bridge National Monument, Utah

The Grand Staircase–Escalante National Monument contains an expanse of stunning rock formations in southern Utah. The monument, established in 1996, spans more than 2,900 square miles and is one of several national parks and reserves located along the Grand Staircase. The layers of sediment, stacked like stair steps, date back as far as 600 million years. Many of these layers include fossils of long-extinct creatures, and the area is a hotspot for paleontologists: In 2002, a gryposaurus fossil, roughly 75 million years old, was found near the monument's Arizona border.