There seems to be a lot of photo evidence suggesting that there is a "fire brigade reservoir built in the form of a swimming pool" within the concentration camp at Auschwitz.
Is it a "fire brigade reservoir", which I assume has something to do with fire safety although I don't know exactly what this means or why they would need it?
On the other hand this seems to have become a rallying point for Holocaust denialism, which makes it hard for me to find trustworthy sources. So what exactly is this structure?