In this episode we explore North America’s largest dry cave system. The Grand Canyon Caverns have no water running through them, so they’re effectively frozen in time… but there is moisture in the air, and no one can work out where it’s coming from.
Hidden underground in several places around the UK are Cold War bunkers which played a pivotal role in monitoring for incoming nuclear bombers. We take you into a bunker which has never been seen on TV before, and another bunker that has been faithfully restored.
And we head to the mountains of Georgia, in Eastern Europe, to visit one of the most spectacular man made cave systems anywhere in the world. Built in the 13th Century, this monastery and military outpost has stood here through huge European and Asian upheaval. But it carries the memories, and bears the battle scars, of its 8 centuries.
