In World War 2, there was a very famous prison camp called Stalag Luft III, for captured Allied airmen. It had the reputation of being escape-proof. There is a great story about three airmen who spent months tunneling out and actually escaped. I won't tell it all here though, I'll just show you this vignette I made of one of the prisoners who made it past the walls and is now tunneling underneath one of the outside "goon-boxes" (watch towers).
Sorry for the bad lighting. It seems I will never get a good photo!