Cave Tours around Austin It's sweat through your shirt hot. So head underground for nature's air conditioning. With constrant temperatures near 70F year-round, caves offer an ideal escape in summer. Natural Bridge Caverns Opening in 1964, Natural Bridge Caverns is the largest commercial cavern in Texas. It offers two tours, Discovery Tour and Hidden Passage Tour. Located at 26495 Natural Bridge Caverns Rd. in Natural Bridge Caverns, outside of San Antonio. … [Read more...] about Cave Tours around Austin