The Crescent Mine Grade is one of the longer sections of trail in Park City, descending almost 4 miles from Thayne's road, down into town. The CMG is built on an old mining train-grade, and thus is a super fast, very straight, and relatively smooth trail. While the corridor and the bench is wide, the tread has since narrowed down to singletrack, making for a rip-roaring descent off the mountain side!
Park City
http://www.singletracks.com/item.php?c=1&i=7529