Foursquare has just put up a new blog post that, among other things, touts the service’s ability to create personalized recommendations, build a location layer for the world, and connect people with all of the places they visit. That’s why tons of appmakers rely on Foursquare to power the location elements of their apps. Cool, nothing wrong with a little bit of self-promotion.

But the really interesting thing that Foursquare unveiled is a map of all of the check-ins (worldwide) over the last three months.

Foursquare did something similar to this back in November, following Hurricane Sandy. They created a timelapse visualization of how the storm affected check-ins in lower Manhattan.

But this new map allows you to zoom in and out on the entire world of check-ins, and even search for specific locations. You can even layer on satellite view and map view atop the check-in data. But it’s a lot more fun to simply look at cities’ structures based on check-ins alone.

For instance, my hometown of Lexington, KY is set up like a wheel with a bunch of spokes. A large road circles the city, and each main road spreads out from the center (downtown) and intersects that main highway. When you look at the city of Lexington on Foursquare’s check-in map, you see this pattern reflected (the main population centers and businesses appear on these roads).

Other, bigger cities also look really cool. Let’s look at Moscow:

You can play around with the check-in map here.

That map is based on check-ins from the last three months, which total 500,000,000. Yep, a half a billion check-ins in 3 months. That’s a pretty impressive figure.