High Quality Content by WIKIPEDIA articles! Rainbow Bridge National Monument is administered by Glen Canyon National Recreation Area, southern Utah, USA. Rainbow Bridge is often described as the world`s highest natural bridge. The span of Rainbow Bridge was reported in 1974 by the Bureau of Reclamation to be 275 feet (84 m), but a laser measurement in 2007 has resulted in a span of 234 feet (71 m). At the top it is 42 feet (13 m) thick and 33 feet (10 m) wide.