Rainbow Bridge is the largest natural bridge in the world, at 290ft high and 275ft wide. A sacred Navajo site, it resembles the graceful arc of a rainbow. Most visitors arrive by boat (www.lakepowell.com, adult/child $126/80), with a 1.2-mile round-trip hike. The natural monument is located on the south shore of Lake Powell, about 50 miles by water from Wahweap Marina in Arizona.
Experienced backpackers can drive on dirt roads to access two unmaintained trails (each 28 miles round-trip) on the Navajo Reservation. Tribal permits are required. Check with the Navajo Parks & Recreation Department for details.