If you took all 7.5 billion humans on Earth, and stuffed them into the same building, how big would it need to be?
It's a pretty out-there question, but it actually has some basis in reality, because there's a town in Alaska where almost every single resident lives in the same building. And there are so many in-built facilities, such as a park, hospital, and hotel, they never have to leave.
But, as the RealLifeLore video below explains, that's just a tiny town - what if we had to house the entire global population within the same walls?
We'll start off with buildings that actually exist, like the AT&T Stadium in Arlington, Texas, which can comfortably seat 80,000 people.
So if living just involved sitting, we could stuff the entire population of Andorra - a tiny European country situated between France and Spain - inside the stadium, with a little room to spare.
But as big as that stadium is, it isn't even the biggest in the world - Rungrado Stadium in Pyongyang, North Korea can seat 114,000 people, which means you can stuff 20 percent of the population of Wyoming inside.
And let's not forget the indoor stadium that the Nazis planned to build, which theoretically could have housed some 180,000 people.
As the video explains, German architects calculated that all the moisture from people breathing inside would have created a whole new internal weather system, complete with artificial rain:
The Nazis also had plans to construct the world's largest outdoor stadium, which would have been capable of seating 405,000 poor souls - more than the entire population of New Orleans.
In true Hitler style, he decided that once he'd secured his victory in World War II, he would force every single Olympic Games for the rest of history to be held in this monster stadium.
Fortunately, that those plans never came to fruition, but here's something that's not - the Great Mosque of Mecca (or Masjid al-Haram) in Saudi Arabia has the capacity to fit 4 million people inside, which means the entire population of Panama, and then some.
And then we have to consider the massive buildings in the world that aren't designed to house people, but could if we really wanted them to.
If we assume that five people per square metre is comfortable enough for the purposes of this thought experiment, the gargantuan Tesla Gigafactory, currently under construction in Nevada, could fit 2,650,000 people.
It looks like that building is actually going to make it to completion, but one that never did is the Crystal Island in Moscow, Russia, which was designed to fit a mind-boggling 12,500,000 people inside - more than the entire population of Belgium.
But what if we wanted to think about things in terms of the total space - not just the floor space - of a single building?
I'll let the video above explain that one to you, but let's just say there's a factory in Washington that could fit an eye-watering 40,831,000 people - but that's just 1 percent of the entire global population.
If we wanted to fit 7.5 billion in a single building? Uh, we're going to need a few more bricks.
Check out the video above to get the answers, and watch part two here.
And when you're done, here's RealLifeLore again with another question: What if everyone lived in just one city?