The house I'm buying has a weird feature. There's a sewer-lid-like opening in the garage. Upon lifting the lid, I see a large room! It's the... basement side room?

Using my deduction skills and questioning people older than me, I've discovered that this room used to be an old cistern.

this is the bottom of the hole
{{gwi:2132639}}

The room is gross. I mean, really gross. You can tell they used to use it for storage so there's rusty metal garage shelves everywhere with moldy wooden planks. I'm getting a dumpster and throwing all of that out. The walls appear to be stone but I can't see them well with the shelves in the way. The house was built in 1959 so it could just be old brick too...

But would it be possible to ever make an old cistern room into a "finished" room?

It's approximately 12'x33'

A fun novelty idea would be to eventually put a slide into the basement from this hole (because who doesn't love a slide entrance into their home?