Bent ' s Old Fort National Historic Site Bent ' s Old Fort ( sometimes referred to as Fort William ) is an 1833 fort located in Otero County in southeastern Colorado , USA . William and Charles Bent , along with 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 permanent settlement on the Santa Fe Trail between Missouri and the Mexican settlements . It was destroyed under mysterious circumstances 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 . The fort was reconstructed and is open to the public . History . The adobe fort quickly became the center of the Bent , St . Vrain Company ' s expanding trade empire , which included Fort Saint Vrain to the north and Fort Adobe to the south , along with company stores in New Mexico at Taos and Santa Fe . The primary trade was with the Southern Cheyenne and Arapaho Indians for buffalo robes . From 1833 to 1849 , the fort was a stopping point along the Santa Fe Trail . It was the only permanent settlement not under the jurisdiction and control of Native Americans or Mexicans . The U . S . Army , explorers , and other travelers stopped at the fort to replenish supplies , such as water and food , and perform needed maintenance to their wagons . The American frontiersman Kit Carson was employed as a hunter by the Bent brothers in 1841 , and regularly visited the Fort . Likewise , the explorer John C . Frémont used the Fort as both a staging area and as a replenishment junction , for his expeditions . During the Mexican - American War in 1846 , the fort became a staging area for Colonel Stephen Watts Kearny ' s " Army of the West " . Ralph Emerson Twitchell makes the following statement . Bent ' s Fort is described as having been a structure built of adobe bricks . It was 180 feet long and 135 feet wide . The walls were 15 feet in height and four feet thick and it was the strongest post at that time west of Ft . Leavenworth . The construction of this fort was commenced in 1828 . . . at a point on the Arkansas somewhere between the present cities of Pueblo and Canyon City , having been disadvantageously located . Four years were required in which to complete the structure . On the northwest and southeast corners were hexagonal bastions , in which were mounted a number of cannon . The walls of the fort served as walls of the rooms , all of which faced inwardly on a court or plaza . The walls were loopholed for musketry , and the entrance was through large wooden gates of very heavy timbers . Destruction . In 1849 when a great cholera epidemic struck the Oklahoma and other plains Indians , William Bent abandoned Bent ' s Fort and moved his headquarters north to Fort Saint Vrain on the South Platte . When he returned south in 1852 , after salvaging what he could , he burned the fort and relocated his trading business to his log trading post at Big Timbers , near what is now Lamar , Colorado . Later , in the fall of 1853 , Bent began building a stone fort on the bluff above Big Timbers , Bent ' s New Fort , where he conducted his trading business until 1860 when the building was leased to the United States government and renamed Fort Wise . It was there that the Treaty of Fort Wise was signed on February 18 , 1861 by the United States and a few Cheyenne and Arapaho chiefs . Old Fort Lyon , as Fort Wise was renamed in 1862 , was built of timber by army troops in 1860 about half a mile west in the Arkansas River bottom . It was abandoned and replaced by new Fort Lyon near what is now Las Animas , Colorado in 1867 . When the fort was reconstructed in 1976 , its authenticity was based on the use of archaeological excavations , paintings and original sketches , diaries and other existing historical data from the period . In popular culture . Restaurant . The historical fort inspired Samuel and Elizabeth Arnold to build a restaurant a few miles southwest of Denver , Colorado named " The Fort " featuring approximations of the architecture , cuisine , and costumes of the Arkansas River region in the 1830s . For example , the restaurant is built of adobe bricks , and serves entrees based around buffalo , elk , quail , huckleberries , and cactus fruit . Some of the waitstaff carry period rifles and powderhorns . The restaurant has attracted a variety of politicians , including Bill Clinton , Boris Yeltsin , Jacques Chirac , and Yoshihiko Noda ; the restaurant ' s owners have been appointed to the Tourism Advisory Board by the U . S . Secretary of Commerce .