The 'going to the sun road' was constructed between 1921 and 1932 and was considered a major engineering feat at that time. Much of the west-facing side of the Rocky Mountains within the park, comprised of the Lewis and Livingston Ranges, features a vertical rock face known as the Garden Wall. The road was literally carved into this cliff The result is a thrilling and hair-raising ride with unbelievable views of both mountains and valleys. The outer edge of the road drops off thousands of feet into the valley below. Driving can be intimidating on a busy summer day because there is very little clearance with oncoming traffic.