Never understood how people doubt the gas chambers' genuineness based on _the material of the doors_. Why _not_ wooden doors? Why should a more robust or gas tight door have been needed? If the material of the door is your "evidence" for the gas chambers being "fake", then you ought to talk to a firefighter and let them tell you how even a pretty badly or even not at all sealed room with some poisonous gas source will easily have everyone in it poisoned.