Colditz Castle in Saxony, Germany, sits high on a precipitous cliff face that towers above a tributary of the river Mulde. First built in the 11th century, the forbidding castle was variously used as a lunatic asylum, a sanatorium for the wealthy, and, through the 1930s, as a prison for enemies of Nazi Germany. In 1939, the castle took on its most famous role: a camp for Allied prisoners of war...