The hatches were a post war addition, the door was fastened by a latch mechanism that could be opened from the INSIDE. In other camps the inside latches were sawn off. There was a film on YT made by a Jewish guy who spent 3 days at Auschwitz, he was joined by Ernst Zundel and they both concluded that the building that was supposed to be a gas chamber was most likely a bomb shelter: it had the remains of a bathroom, a kitchen and there was clearly a telephone connection! The ovens were used for burning lice infected clothing and hair - they were way too small to process bodies. A modern crematorium takes a considerable time to reduce bodies to ashes at very high temperatures - there was no way these ovens could have burnt bodies. I could go on: the most damming point was there were NO traces of zyklon in the fabric of the building. Where this was used as a delousing agent, the walls were stained blue. So many other points that clearly show the mass extinction program highly unlikely.