Bent's Old Fort National Historic Site  Bent's Old Fort is an 1833 fort located in Otero County in southeastern Colorado, United States. A company owned by Charles Bent and William Bent and Ceran St. Vrain built the fort to trade with Southern Cheyenne and Arapaho Plains Indians and trappers for buffalo robes. For much of its 16-year history, the fort was the only major white American permanent settlement on the Santa Fe Trail between Missouri and the Mexican settlements. It was destroyed in 1849. The area of the fort was designated a National Historic Site under the National Park Service on June 3, 1960. It was further designated a National Historic Landmark later that year on December 19, 1960.