From the record
“Ashcroft is an extinct mining town located in Pitkin County, Colorado, United States. The silver mining camp was founded as Castle Forks City in the spring of 1880.”
Wikipedia article Ashcroft, Colorado, CC BY-SA 4.0.
One of 38 National Register listings published here for Pitkin County · listed in 1975 · category: Site.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service · the Wikipedia article