This is an easy day-trip from Phoenix. It's about 2 1/2 hours north. (17 miles north of Payson) At a cool elevation of 4,530 feet, it is a welcome retreat from the heat of the desert.
Tonto Natural Bridge is thought to be the largest natural travertine bridge in the world. This scenic place is open year-round except Christmas, and is only $3 for admission.
There are 4 good viewpoints from above the cave. If you do venture through the passage, be aware that the rock inside the cave is extremely slick. The area is also prone to flash-flooding.