Un-curious people are a mystery to me - how can you live your life and not ask questions about STUFF
The place I have been going to yoga is in a basement of this very old building (for Toronto standards). One of the rooms looks like a vault. I asked one of the instructors - “this looks like some sort of vault” and they said “I never thought about it, yeah, this door is very big and heavy”
So I did my research (tm)
