Door into Mauthausen gas chamber
The photo above shows the outside of the door on the west wall of the gas chamber. Note the light switch on the left side and the peephole in the center of the door. According to the US Holocaust Memorial Museum, top Nazi officials Heinrich Himmler, Baldur von Schirach and Ernst Kaltenbrunner viewed the gassing procedure through the peepholes in the two doors into the gas chamber when they visited the Mauthausen camp to inspect the factories there.
This is a close-up of the peephole through the door on the west wall of the gas chamber; it was taken from the outside of the door. The glass had been broken out of the peephole when this photo was taken in May 2003.
The photo above shows the latch and the handle on the outside of a door into the gas chamber. The black object in the upper left-hand corner is a light switch. Note that the wall outside the door is covered with white ceramic tile which matches the tile inside the gas chamber.
This photo shows the interior side of the same door. Note that there is no way of opening the door from the inside if the latch handle is turned to the horizontal position on the outside.