Assay Museum at Wall Street, next to the monolithic wall in Four Mile Canyon, is open and staffed with local volunteers.
The volunteers were well-informed, well-connected in the canyon area, and truly interested in their work at the office. The stories they told focused largely on the people involved in the mill and assay office, most especially Delores Bailey, descendant of the men who bought the office from the mill and converted it to a residence.
While I personally find the human stories only mildly interesting--I know I'm something of an outlier in saying so--I did find a couple of publications of great interest. One is the story of the local community written by Ms Bailey, called God's country U.S.A., subtitled the life and history of milling, mining, and families along the Switzerland Trail. This is one I will purchase, available from her daughter in Prescott Valley AZ as well as from Tom McMichen, Cultural History Interpretive Coordinator for Boulder County Parks and Open Space Department.
The Switzerland Trail ROW is perhaps 50 feet south of the Assay Office, across what is now a meandering creek about four feet wide trickling down through the heavy overgrowth. I had to bushwack my way even to see the creek, the woods are now so heavily overgrown. Four Mile Canyon at this location is at most 75 yards wide. With the occasional massive storms we still see these days, it's easy to imagine a wall of water exploding through the narrow opening, washing everything away.