In 2015, the former head of Russian Railways proposed building a massive superhighway linking Europe and North America through the Bering Strait, creating a route that could one day make overland travel from London to New York possible. The Bering Strait, which separates Russia and Alaska, is only about 85 kilometers (53 miles) wide at its narrowest point. For more than a century, engineers, governments, and visionaries have proposed building a bridge or tunnel across it, creating the first permanent land connection between Asia and North America. The two Diomede Islands, located roughly halfway across the strait, could serve as natural stepping stones for such a project. Today, most proposals favor a tunnel over a bridge, as Arctic sea ice, harsh weather, and seismic activity would make a bridge extremely difficult to build and maintain. The crossing itself is not considered the greatest challenge; the real obstacle is the lack of infrastructure on either side. Thousands of miles of new roads and railways would have to be constructed through some of the most remote and sparsely populated regions on Earth. Supporters argue that a Bering Strait crossing could eventually connect the transportation networks of Eurasia and North America, allowing freight and passengers to travel continuously by land between the two continents. In theory, it could even make an overland journey from London to New York possible. Despite repeated interest since the early 1900s, the enormous cost, engineering hurdles, and geopolitical tensions have kept the idea from progressing beyond the proposal stage.(Historic Vids)