Trail Ridge Road

48 paved miles across Rocky Mountain National Park between Estes Park on the east and Grand Lake on the west, topping out at 12,183 feet. Long stretches run above treeline with no guardrail on the drop side, and weather at the high point can turn to snow or lightning in any month. The park advises setting aside at least half a day. The road is closed by snow through the winter and reopens only after plowing crews break through in late spring.