The Great Siege Tunnels came first, but the World War II Tunnels are the real main event of Gibraltar’s tunnels. The introduction of machinery obviously helped, but the urgency of fascism’s onslaught added an extra layer of chaos to the construction of this network. Work took place day and night and day again, creating a quite incredible underground city that contained power stations to keep soldiers going, barracks, hospitals and all the rest. These tunnels allowed trucks and ambulances to drive straight into the Rock, which blows our mind every single time. North Africa and Rommel were invaded by here, and the tunnels went from a strategic necessity to an eventual tourist attraction, 24 miles of magic that feels like a different world to that on the other side of the Rock.