Ever been in a hotel so big that it's made you wonder just how many people could live in it if every single room was full, and if its guests never left?
That's basically what has happened in the massive Regent International in China's Qianjiang Century City - it was built to be a hotel, but those plans were abandoned and it's now simply an enormous block of apartments, with an astonishing 20,000 people living there.
The Regent International is 675ft tall, making it a huge building, with an unusual S-shaped design.
Amazingly, those 20,000 residents haven't even filled the building completely - its maximum capacity is around 30,000 people, so there's room for another 10,000 to arrive.
Advert
Those are slightly mad numbers, and things become even more dystopian when you learn that the building houses a whole bunch of amenities so that these 20,000 people don't have to actually ever leave.
There are shops embedded in the building, including a food court, nail salons, swimming pools, barbers, supermarkets and internet cafes.
This means that basically every need you might have should be available within the Regent International, making it a sort of town in a building (with a pretty chunky population compared to many towns, too).
For such a huge building, there aren't that many ways to glimpse its interior, though - residents don't seem to have posted much about it.
Instead, we're reliant on scant social media clips that have emerged, including some pretty amazing exterior footage of the building's sheer size captured by drone.
One TikTok creator did show a little of the building's inside as she apparently made her way around it, although you only really get to glimpse the building's foyer, rather than getting a real sense of the geography of its corridors.
Still, people in the comments under those videos are in awe at the scale of the building - one person wrote: "My town only allows for minimum 1/2 acre plots. My neighbors are still to close even with that. I could never live in that building."
Another asked an ironic, but quite fair question: "If you work in that restaurant and live in the same building; are you working from home?"
Just think about it - could you happily live in a building of this size? After all, it's one thing living in a mid-size apartment block, but quite another living in one of the most densely populated buildings you could possibly hope to find. Just think of how many neighbors you'd have!