"All hope abandon, ye who enter in!" wrote Dante Alighieri in the third Canto of his Divine Comedy. He was about to set foot in Hell. Entering a tunnel is obviously a different experience: it's shorter, safer and you don't need Virgil beside you to undertake the task. Like in Dante's Hell, though, even at the entrance of a tunnel you can hardly see its end. In tunnels, wanderers find themselves sorrounded by darkness, on a claustrophobic path through a holed mountain or under a digged ground. It sounds creepy, but don't worry: you can always go forth to see again the stars at the end of it.