Pompeys Pillar was designated as a National Monument in January 2001. Prior to its monument status, it was a designated National Historic Landmark in 1965. It was part of the original 1803 Louisiana Purchase. Pompeys Pillar represents the legacy of the early West and its development. At the Pillar, there is evidence of Native Americans, early explorers, fur trappers, the U.S. Cavalry, railroad development and early homesteaders, many of whom left their history embedded in this sandstone pillar. Captain William Clark, his guide, Sacagawea, her 18-month old son (nicknamed "Pompey") and a crew of 11 men stopped near the 200-foot-high rock outcropping on the return leg of the Lewis and Clark Expedition. On July 25, 1806, Clark carved his signature and the date in the rock and recorded doing so in his journal. The historic signature remains today, and visitors can walk on a boardwalk to see it. When the Monument is open from the beginning of May through the beginning of September, a $7 entrance fee is charged for each vehicle. 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. Commercial/Group Vehicle Fees Commercial and organized group rates are based on vehicle capacity. Vehicles capable of seating 6 passengers and under--$25 Vehicles capable of seating 7-25 passengers--$40 Vehicles capable of seating 26+ passengers--$100 Even when the Monument is closed, visitors may still walk into the site during daylight hours. The walk from the gates to the Pillar is about 3/4 mile. Facilities available are the boardwalks, walkways, and vault toilets. All buildings will be closed.