This is one of the more disappointing items I've posted here, as the location itself is disappointing. This is the site of the former Ft. Sanders, Wyoming, just outside of Laramie Wyoming
Ft. Sanders isn't a fort we think of much in terms of Frontier, or Wyoming, history. It was a small post along the Union Pacific, and as such it seemingly figured in the story of the Indian Wars less than some others we'd typically consider. This doesn't mean it wasn't a significant post in its own way, but it wasn't a major post like Ft. Laramie, nor was it one that was on the ragged edge of the Indian frontier, like Ft. Caspar or Ft. Reno.
And there's very little left of it. As the Wyoming sign commemorating it notes, the mostly wooden post is now mostly gone. The brick building above was the powder magazine. I couldn't spot the guard house when I was there, but I understand it to still exist, and to be across the highway, so I'll have to update this entry once I find it. The sign is somewhat inaccurate as apparently some structures that were on the post were moved into Laramie for private use and still exist, and The Cavalryman Restaurant, depicted in the photograph above, was a post structure.