At 11,493 feet, Boreas Pass is the high point on the dirt road following the old railway between the cities of Breckenridge and Como. When running, a trip up to the pass and back down to the car is suffice, but bikes and cars often do the entire road, lined with mining history, connecting the two towns.
There are a couple areas to park a car along the roadway, so you don't have to start from the bottom. Plus, there are basically sporadic views the entirety of the road, so making it to the pass is just icing on the cake.