When: April 11-30, 9 a.m.-6 p.m., $7-$14. Meramec Caverns, I-44 west from St. Louis, exit 230, (follow the many, many billboards), Stanton, 800-676-6105, http://www.americascave.com.
This cave is so big, it accommodates a gift shop, a restaurant, a snack bar and a museum. On the one-mile tours, which last one hour and twenty minutes, you will enjoy 60-degree temperatures and beautiful nature. Tours leave every 20-30 minutes.