The Natural Bridge Caverns are the largest known commercial caverns in the U.S. state of Texas.The name was derived from the 60 ft natural limestone slab bridge that spans the amphitheater setting of the cavern's entrance. The span was left suspended when a sinkhole collapsed below it.The caverns are located near the city of San Antonio, Texas in the Texas Hill Country next to the Natural Bridge Wildlife Ranch, a drive-through wildlife safari park.