To create an impregnable Maginot Line on Germany\'s eastern front, Adolf Hitler built the
To create an impregnable Maginot Line on Germany's eastern front, Adolf Hitler built the "Oder-Warthe Crescent", a gigantic underground system of bunkers connected by miles of labyrinthine passages. But by 1945 only twenty miles of it had been built. Now this system is a haven for spelunkers. Equipped with caplamps, ropes and self-made maps, three men from the town of Loebau in Saxony clamber through the monstrous fortifications to explore their every nook and cranny.