The gas chamber at Natzweiler was built for Dr. August Hirt, in order to enable him to gas Jews for his work on racial differences. Hirt's superior, Sievers, submitted to SS Sturmbannfuehrer Dr. Brandt in a letter headed "secret" on the 9th of February, 1942, Hirt's "proposal for securing the skulls of Jewish-Bolshevik Commissars:" "...Of the Jewish race, however, only so very few specimens of skulls are at the disposal of science that a study of them does not permit precise conclusions. The war in the East now presents us with the opportunity to remedy this shortage. By procuring the skulls of Jewish-Bolshevik Commissars, who personify a repulsive yet characteristic subhumanity, we have the opportunity of obtaining tangible scientific evidence." 
Please forgive varying image quality...we are working on the site. All photographs and text Copyright © Diana Mara Henry.
Across the street from the gas chamber is an inn, popular with skiiers before Worl War II, that continues to be used today as it did during the war, when diners might see naked prisoners being herded inside. For an interesting rendition of this, see Judy Chicago's Holocaust Project, which contains an extensive report and drawings of the camp.

School girl by vats where the bodies of Jews gassed in the chamber were stored in alcohol until they could be firther dissected and "studied" by Dr. August Hirt, the ambitious and lazy scientist who developed this get-ahead scheme and received funding for it from the Ahnenherbe, a Nazi semi-occult semi-academic group funded by the SS, for the "study of ancestors." 
One of the images presented at the Nuremberg trials, in the "Medical Case," documenting the bodies as they were found in the vats at Natzweiler. The cadavers have Auschwitz numbers tattooed on their arms.
Augut Hirt disappeared and was never found
The gas chamber was constructed so that the proceedings as people were dying could be observed, after the door was closed and a component of the lethal mixture poured into the chamber through the hole visible in the wall next to the girl's arm. The procedure was clinically described by Josef Kramer, Commandant of Natzweiler for much of its existence, during his trial as "the Beast of Belsen," where he was reassigned after Natzweiler was vacated ahead of the approaching U.S. army in the fall of 1944. Kramer is the only Nazi at natzweiler to have been executed for his crimes.
Gypsies were also gassed at Natzweiler, in experiments conducted by Dr. Hagen to develop an antidote to mustard gas. These experiments are also documented in the Medical Cas of the Nuremberg trials. The man seen here in front of the gas chamber's plaque is a Gypsy who claims to have survived one of these gassings, as a 17 year old.