in a concrete room

‪Me: “Do you think it’s a good idea for you to run around playing tag in a small concrete room, with concrete walls and floors, with a 10yr old?“‬
‪5yo: "Yes."‬
‪Me: "When you get hurt, I’ll give you hugs - but not sympathy."‬
‪5yo: "Okay!"‬
**runs off to play**

There’s a props room under my auditorium at school. I’m Head of Set for our school’s latest musical, and so me and my two guy friends went down to investigate stock.
One of them found a door behind a bunch of props in a hard to reach place, and so we used our key. It fit. What we found was a small concrete room. The air was cold, and there were vents and pipes on the walls and roof. According to a chart it hadn’t been entered since 1998.
We’ve added a table and chairs and use it for Dungeons and Dragons. No one knows.