Have you ever wondered why the world’s largest cities sprout up where they sprout up? It has a lot to do with water, natural resources, history, and being in the northern hemisphere.

Wendover Productions took a really hard look at why cities are whey they are in the video below and it’s completely fascinating. Some of the reasons are pretty obvious: Being close to water helps because the ocean is what connects the world, and without access to drinkable water cities would die of thirst. Being near natural resources obviously helps, too, since living near the stuff you need just makes sense.

But what’s most interesting is probably how most of the big cities in the world are located in the northern hemisphere, and that’s because many of history’s largest empires were located in Europe and Asia. And many of history’s largest empires were located in Europe and Asia because the shape of both Europe and Asia is wider than it is tall. And being a wider continent means there’s a lot of land that’s roughly on the same latitude which means roughly the same climate, which means plants and animals that were successful on one part of the continent can probably be successfully raised in another part of the continent (or even a new continent along the same latitude like say, North America), which means towns and colonies can support more people, which means they can eventually become the biggest cities in the world.