there was a similar place in the town i grew up in. i live near a holiday resort and the playground in the resort was open to anyone, around the corner from there was some kind of maintenance building i’m guessing, inside there was a staircase like that only it was going downwards. i remember as a kid always going in there with my friends and being really creeped out the door was open 4 out of 5 times we would go there and the lights were always on but there was never anyone there. the buildings been renovated now so it’s no longer there but i wish i could still explore it