Hours: Mon.-Sat. 9-5, Sun. 10-5, June-Aug.; Mon.-Sat. 9-5, Sun. 11-5, Apr.-May and Sept.-Oct.; Mon.-Sat. 9-4, Sun. 11-4, rest of year. Forty-minute shuttle bus tours board hourly (half-hourly June-Aug.) at 10 a.m. at the visitor center; last bus leaves at 4 p.m. (May-Oct.) and 3 p.m. (rest of year). Closed Jan. 1, Thanksgiving and Christmas.