That looks like Ptarmigan Lake, just below the top of Imogene Pass - there's a small stone fort at the top of the pass called Fort Peabody, named after the Colorado Governor who stationed National Guard troops there during the labor strikes at Telluride in around 1903. The troops were there to keep deported strikers from walking back into the Telluride mines over the pass from Ouray. They were there all winter - this is at about 13,200 feet at the Fort!!!
Yikes - not my idea of a great place to spend the winter! A super 4WD trip, though.
The big round thing with the holes is a steam boiler - most of the mines used steam power, mostly powered by coal after all the trees were cut down, and this site is way above treeline anyway. This led to the world's first commercial AC power plant at nearby Ames, Colorado in about 1891 or 1892.
Fascinating area to come explore, particularly with 4WD - most trails are moderate in difficulty. Peak color averages around October 1st, plus or minus a week.