The Great Escape (1963)

During WWII, the Germans decide to build an escape-proof camp and move all of the frequent-escapers to it. Since the Allied forces are duty-bound to do their best to escape if captured, the prisoners work together to execute the most elaborate and, hopefully, resource-diverting breakout possible.

This is a fascinating film made all the more incredible by the fact that it's a true story. Though long, we were never bored. 

B+