In 1943 the Third Reich Germany had begun building huge underground complexes in the Góry Sowie ("Owl Mountains") region of Lower Silesia. Known under the code name "Riese" (German for "Giant"), they were never finished and their destiny is still a mystery. Were they meant to be military plants? Depots for stolen treasures? Hitler's headquarters? Nuclear laboratories?
Three of seven complexes are now tourist attractions open to the public. Here we are in the entrance parts of the Rzeczka complex, a system of corridors half a kilometre long. On the walls you can see plans of all the complexes.