Stalag Luft III in Żagań

You're standing near Żagań in Poland, on the site of Stalag Luft III. During the Second World War this was a German camp for captured Allied airmen. Back then the town was called Sagan, and it was part of Germany. Take a look at the ground under your feet. That soil is exactly why the Germans picked this spot. Beneath a dark grey top layer lies loose, bright yellow sand. A tunnel dug in it collapses easily. And anyone with yellow sand on his clothes gave himself away. The huts were also raised about sixty centimetres off the ground, and microphones around the camp listened for the sound of digging.