Pompeys Pillar National Monument

Pompeys Pillar contains the signature of Captain William Clark of the Lewis and Clark Expedition. Clark’s inscription is the expedition’s only remaining physical evidence visible on the Corp of Discovery’s trail. An interpretive center at the site recounts Clark’s journey through the Yellowstone Valley in 1806. The Pillar overlooks the Yellowstone River about 25 miles east of Billings, Montana.

The Pillar overlooks the Yellowstone River about 25 miles east of Billings, Montana. The area is easily accessible from Interstate 94, using exit 23, or from Montana Highway 312. The Pillar is a sandstone butte or mesa and covers about two acres at its base and stands about 150 feet high. Because it is the only sandstone outcrop on the south side of the Yellowstone River for several miles in either direction, it has been a landmark for centuries.