The historic art bunker is a tunnel system under the Nuremberg Castle and forms a station of the Nuremberg Historic Mile. The rock passages have been created in the hard sandstone since the Middle Ages. From 1939, at the instigation of the then director of the Germanic National Museum Heinrich Kohlhaußen, numerous of these rock passages were used to protect works of art from bombing raids. From summer 1940 the rock cellar Obere Schmiedgasse 52 was reconstructed in 1941 the Neutorturm cellar, and from 1943, the passage under the palace was also turned into art bunker. The reconstruction ensured heating, ventilation, and drainage; the bunker extends up to 24 meters deep and supplies optimal conditions. Today the shelter is the first fully automated museum in Nuremberg.