The Bent-St. Vrain Company built Bent's Fort, an elaborate adobe fort on the eastern Colorado plains, along the Santa Fe Trail. Bent's Fort was the only privately owned fortification in the west. It became a premier trading center and rendezvous for fur trappers. Bent's Fort has been restored and is listed on the National Register of Historic Places as a National Historic Site. Ceran St. Vrain also helped establish what is now called Old Fort Saint Vrain, along the South Platte River.