Eisenhower Memorial Tunnel

As you travel west along I–70 you'll reach one of the world's engineering marvels, the 8,941-foot-long Eisenhower Memorial Tunnel. Most people who drive through take its presence for granted, but until the first lanes were opened in 1973 the only route west through the mountains was the perilous Loveland Pass, a heart-pounding roller-coaster ride. In truly inclement weather the Eastern and Western slopes were completely cut off from each other. Authorities first proposed the tunnel in 1937. Geologists warned about unstable rock, and through more than three decades of construction, their direst predictions came true as rock walls crumbled, steel girders buckled, and gas pockets caused mysterious explosions. When the project was finally completed, more than 500,000 cubic yards of solid granite had been removed from Mount Trelease. The original cost estimate was $1 million; by the time the second bore was completed in 1979 the tunnel's cost had skyrocketed to $340 million. Today there can be a long wait during busy weekends because so many travelers use I–70.