Pompeys Pillar National Monument encompasses 51 acres on the banks of the Yellowstone River with a massive sandstone outcrop covering about 2 acres at its base and rising 120 feet high toward Montana's Big Sky. The monument's premier location at a natural ford in the Yellowstone River, and its geologic distinction as the only major sandstone formation in the area, has made Pompeys Pillar a celebrated landmark and outstanding observation point for more than eleven thousand years of human occupation. Hundreds of markings, petroglyphs, and inscriptions left by visitors including William Clark and the Lewis and Clark Expedition have transformed this geologic phenomenon into a living journal of the American West.
The Interpretive Center located at the Monument relates the journey of Captain William Clark and his detachment down the Yellowstone River Valley in 1806. It also addresses tribal culture, flora and fauna, the Lewis and Clark Expedition, and the historic legacy of Pompeys Pillar through the changes of the 1800s. There is a gift shop, restrooms, and a water fountain located in the center.
The Monument is open year-round for walk-in visitors from dawn to dusk. Between May and September, when the front gate (hours 8:30am-4:30pm) and interpretive center (hours 9:00am-4:00pm) are open, a standard fee is charged for each vehicle based on passenger occupancy. There is no separate fee for the interpretive center. All fees are returned to the site and used to maintain and improve the facility. All valid federal recreation passes are honored at the site.
The site also features outdoor interpretive exhibits, picnic tables, hiking trails and vault toilets. Pets must be on a leash at all times. Day use only, no overnight camping permitted.
If available, print out a copy of your pass to place on the dashboard of your vehicle.