Tunnel 57

Tunnel 57 was a tunnel under the Berlin Wall that on the 3rd and 4th October 1964 was the location of a mass escape by 57 East Berlin citizens. Student and future astronaut Reinhard Furrer was among the West German escape helpers who assisted the East Berliners in escaping. During the escape, East German border guards came upon the scene. A West German escape helper, Christian Zobel, opened fire, the bullet piercing the lung of young East German guard Egon Schultz, who was then fatally wounded by friendly fire from another guard. This friendly fire was kept secret by the GDR government.

A memorial plaque on the site today commemorates both the successful escape, and Schultz's death as a victim of the Berlin Wall.

Source: Wikipedia