Tonto Natural Bridge in Arizona is widely regarded as the world’s largest natural travertine bridge, spanning a tunnel more than 400 feet long and rising 183 feet high. It entered recorded history in 1877, when David Gowan documented it, later brought his family there, and linked the site’s early settlement to their long residence. After Gowan’s death in 1926, the family remained near the bridge until 1948. That year Glen L. Randall and his family bought the bridge, lodge, and surrounding acreage. The property later became a state park, where the historic lodge still stands and visitors reach the bridge by short hiking trails.