One of the world's premier caverns, take 75-minute tour through a half-mile of the largest show cavern in Texas. For the more daring spelunker, the Adventure Tour offers a physically demanding excursion into an undeveloped cavern (reservations are required for the Adventure Tour). Also, visit the Natural Bridge Mining Company and pan for gemstones. A gift shop, snack bar and picnic grounds also available. Take exit 175 on I-35; eight miles west on Natural Bridge Caverns Rd. (F.M. 3009).