Maybe that's because it's also one of the world's steepest roads, chiseled into the mountain by local villagers. The Guoliang Tunnel is located ... a one-of-a-kind ride through the mountains.

The greatest mining project now being carried out in the West is a tunnel which is being driven into Palmer Mountain 8,400 feet, through 1,400 acres of mineral-bearing ground. The tunnel has ...

Russia plans to build the world's longest undersea tunnel, a 64-mile transport and pipeline link that would run from Siberia to Alaska and supply the United States with oil, natural gas and ...