The White Pass and Yukon Route is a narrow gauge railroad linking the port of Skagway, Alaska, with Whitehorse, the capital of Yukon. Completed in 1900, the railroad makes a number of cliff-hanging turns. (Flickr/HBarrison)

Built in 1898 during the Klondike Gold Rush, the narrow-gauge railroad (also called "the railway built of gold") connects the port of Skagway, Alaska to Whitehorse, Yukon. The route, if you are fond of cliff-hanging turns and steep climbs, is one of the most scenic in the world. The railroad climbs almost 3,000 feet in just 20 miles with steep grades of up to 3.9 percent, according to its website. Passengers on the vintage-style cars enjoy breathtaking views of mountains, glaciers, gorges, and waterfalls.