Pompeys Pillar National Monument, Natural sandstone monument in Yellowstone County, Montana, United States
The sandstone formation rises 150 feet above the Yellowstone River, covering an area of 51 acres along the riverbank in south central Montana.
William Clark carved his signature into the rock on July 25, 1806, during the Lewis and Clark Expedition, creating the only physical evidence of their journey.
The sandstone surface contains over 5,000 petroglyphs and pictographs from Native Americans, fur trappers, military expeditions, and railroad workers throughout centuries.
The monument opens from May through September, with an interpretive center operating daily between 9:00 AM and 4:00 PM, offering exhibits about the Lewis and Clark Expedition.
The geological formation stands as the single major sandstone outcrop in the region, serving as a natural registry for 11,000 years of human presence.
Location: Yellowstone County
Inception: 2001
Website: http://www.blm.gov/publish/content/mt/en/prog/nlcs_new/POMPEYSPILLAR_NM.html
Operator: BLM
Website: http://blm.gov/publish/content/mt/en/prog/nlcs_new/POMPEYSPILLAR_NM.html
GPS coordinates: 45.99530,-108.00600
Latest update: May 27, 2025 08:45
Montana hosts natural and historic sites ranging from the limestone gorges of Bighorn Canyon, where red cliffs rise over 300 meters, to the Makoshika badlands dotted with dinosaur fossils. Visitors explore the boiling River near Gardiner, where thermal springs blend with the cold waters of the Gardner River, or cross the Kootenai suspension bridge that spans the river for 64 meters. The state also preserves traces of its past with the Pompeys Pillar, a sandstone formation bearing William Clark's signature from 1806, and the Gates of the Mountains, a canyon named by Meriwether Lewis during the 1805 expedition. From craft distilleries like Glacier Distilling Company in Coram, old railway infrastructures converted into accommodations, to artistic installations such as the Blue Horses in Three Forks, Montana offers a variety of discoveries for travelers exploring its regions.
Lewis and Clark National Historic Trail
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First Interstate Center
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Rimrocks
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Moss Mansion
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ZooMontana
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Little Bighorn Battlefield National Monument
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Rimrock Auto Arena at MetraPark
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Lake Elmo State Park
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Western Heritage Center
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St. Patrick's Co-Cathedral
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Alberta Bair Theater
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Pictograph Cave State Park
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Roundup Central School
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The Reef
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St. Benedict's Catholic School
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Prescott Commons
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St. Joseph's Catholic Church
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Masonic Temple
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First Baptist Church
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Austin North House
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John Boyum House
42.3 km
Billings Chamber of Commerce Building
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Moss Mansion Museum
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James J. Sullivan House
42.6 km
Babcock Theatre
45.5 km
Yellowstone Kelly Interpretive Site
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Saint Patrick Co-Cathedral (Billings, Montana)
45.8 kmReviews
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