The Sahara Desert is, without exaggeration, one of the harshest regions on the planet. But most people know that, to some degree. What’s often underappreciated, though, is just how massive it is. It is by far the largest hot desert on the planet. And, in fact, for a comparison, it’s about a million square kilometres larger than the contiguous United States. Now imagine trying to cross it, let alone build something across. That is exactly what happened in the 1880s, and the results would be horrifying, but not just because of the harsh terrain. 1880 Trans-Saharan Expedition