An actual manhole cover, this is either going to transcend shitpost or literally define it.
Nobody in their right mind would put that inside, so was either built by someone not in the right mind or an extension that just paved right over it.
Manhole covers are used for structural rigidity and tamper prevention.
First (and most hopeful) thing that would come to mind is a rainwater sewer.
No idea of country of origin, it could be someone’s idea of a protective measure for a boundary trap If the sewer main runs directly under the property which would be a bit unusual.
If it is a shaft to a regular sewer, I think you’d smell that.
Rent’s going to go crazy if it turns out to be a parallel dimension attached to a mansion or something.
It’s probably a chute for an old coal or wood heater. These are pretty common in houses built in the late 19th and early 20th century in the US.
IIRC this was a reddit post, but without the Snapchat text. I do have a vague memory of the OP being from Britain and that they came to the conclusion that it was some sort of sediment tank.
Oldest instance of that image from Tineye.com
edit: https://www.reddit.com/r/WTF/comments/gj1gea/i_bet_this_wasnt_on_the_zillow_page/
