- An Arizona Natural Wonder Welcome to the Grand Canyon Caverns Grand Canyon Caverns located on Route 66, twenty-two miles west of Seligman, AZ, has limestone walls formed in prehistoric times by an inland sea. Fossils and the bones of long-extinct animals have been found in the Caverns. Although Grand Canyon Caverns has been open to the public for over 74 years, each year new discoveries and ...www.gccaverns.com