Jewel Cave was discovered in 1900 and was run as a tourist attraction for many years. It was made a national monument in 1934 and today uniformed rangers guide visitors through its crystal-lined passages. Nearby Jasper Cave is also an adventure and is not for the fainthearted. Both caves are in the 1300-acre national monument, about 16 miles west of Custer on US 16. Submitted by: Henry Chenoweth.