Ian,
That's Gunsight Pass out of Crested Butte. The picture is a three picture stich. It's really a wide panorama. It's a fun trail. I wanted to go over the top but wasn't sure if the trail would continue or if I would have to come back the same way. I was alone and the off cambor switchback looked precarious. There were no tire tracks at all. There's a road closed sign before you even get to the top.
This is the backside trail I wouldn't do alone:


There's a little known trail out of Marble that's really fun. It goes up to the top of Treasure Mountain. You can see the Schofield road and spring ice jam from up there. It's mostly steep 2 point switchbacks. It's so seldom used there's wild flowers growing in the middle of the road in the spring! The road to Marble is at the bottom of this picture:



Here's the trail in July:



If you want to do it ask the locals in Marble or PM for details.

Ron