Pompeys Pillar is a giant sandstone rock containing the only physical evidence of the route taken by Lewis and Clark during their monumental exploration of the American west. Captain William Clark stopped at the pillar and took the time to carve his name and the date, July 25, 1806, into the soft rock. He was on his way back east, following the Yellowstone valley.

Clark’s signature is still there, protected by a brass casing with a bulletproof glass cover. Now a national monument, Pompeys Pillar is easily explored on foot. A trail leads past an open area and then climbs the rock. One branch of the trail leads to the area in which Clark (and many others) left marks in the rock. The other branch climbs to the top of the pillar, with panoramic views in all directions. The view of the Yellowstone river is most impressive and well worth the short climb. Pompeys Pillar National Monument is about 25 miles east of Billings, Montana.