These are the foundation remains of the Eureka Mine and Mill in Eureka, CO.   Eureka is a ghost town today and is located a few miles north from Silverton on the Alpine Scenic Loop.   This was a massive complex and it's timbers may have been dismantled and relocated to the Sunnyside Mine in the mountains above Eureka.   There is a scale figure reference in the image on the extreme left at grade.

Image of the Eureka Mine complex before it was dismantled.