Hidden Valley was a local ski area attraction in Rocky Mountain National Park from 1955 - 1991. It is located off of Trail Ridge Road and still has the ski lodge at the base of the mountain and next to the parking lot.
You can snowshoe or attach skins to your downhill skis and get to the top of the ski area, at about 12,000'. All winter long, if there is snow on the trails, you'll see people snowshoeing or skiing the trails that are still wide enough as RMNP is letting the area go back to its natural state.
This time we decided to snowshoe to the top of the trails (as there is another section of the bowl higher up). It was a gorgeous day (a bit windy) and we seemed to capture the aura of Hidden Valley in the video.