While we were at Fort Carson today, Ethan and I took a few moments to go over to the retreat ceremony. The ceremony is held each evening at 5 PM, at Founders' Field, in front of Headquarters 4th Infantry Division.
Here is an article on the history of the retreat ceremony, taken from the Fort Hood Sentinel.
When we arrived, a color detail was waiting in the covered stands near the flagpole. Founders' Field also serves as a parade ground; these are the reviewing stands.
The detail formed up and marched to the flagpole, and stood waiting. At precisely 5 PM, the Retreat bugle call sounded, followed by a shot from a cannon on the edge of the field. To the Colors then sounded, and the detail lowered the flag.
These photos show the detail folding the flag.