Answer: What In The World Happened Here? LXXXIX: (89)
This was the entrance to "Harry", the successful tunnel in the Great Escape. Paul Brickhill wrote the book. The movie starring Steve McQueen took a lot of liberties with the facts - at least as far as motorcycles were involved. Although only three tunnelers returned to England, the war effort in Germany was affected by the half a million soldiers and police required to conduct a search for the escapees. Fifty escapees were shot by the Nazis in cold blood. Stalag Luft III was evacuated on the anniversary of the posting.
Verum audaces non gerunt indusia alba. - Ipsi dixit MCMLXXII