Then in late 2013 it became a rehabilitative transitional housing facility for homeless people with some form of substance abuse problem.

Part of the site, the Fort Lyon National Cemetery, which began burials in 1907, remains open.

In July 1860, the Army rented Bent's New Fort and used it for storage of annuity goods for the Cheyenne and Arapaho.

[2][a] Annuity goods were provided by treaties in exchange for reduced access to ancestral land, such as hunting grounds.

[7] Old Fort Lyon was the staging post used by Colonel John Chivington in 1864 as he led an attack on friendly Cheyenne and Arapaho camps that became known as the Sand Creek massacre.

[7][8] In 1866 after flooding on the Arkansas River, the U.S. Army relocated Ft. Lyon 20 miles upstream to a site near Las Animas.