1. A map showing homicide rates around the world.

2. A map of how common blonde hair is around the world.

3. A map drawn in imperial Japan in 1853, centring on Tokyo.

4. A map of the world in 43 AD: a reprint of one drawn by Pomponius Mela, a Roman scholar credited as the father of geography.

Reconstructed in 1898 by Konrad Miller.
5. A map showing how the official time and the solar time differs around the world.

Taken from Stefano Maggiolo's fascinating blog.
6. A map showing every city in the world with more than 100,000 inhabitants.

There are 4,037 of them.
7. Relatedly, a map showing the population density around the world.

8. Sticking with population: This is how big each country would be if it were in proportion with its population.

9. A map of the world as seen by the Ottoman Empire in 1803.

From the Cedid Atlas Tercümesi (The New Great Atlas).
10. A map of the prevailing religions in countries around the world.

Which, annoyingly, doesn't include "no religion" (which would be the biggest single group in much of Europe), but still.
11. A map of the world from 1154.

Drawn by the Arabic cartographer Mohammed Idrisi, from the Tabula Rogeriana (Book of Roger).
12. A map showing where you'd end up if you dug straight down to the other side of the Earth.

Assuming you could find a way not to be crushed and burned to death on the way, of course.
13. The Mercator projection, 1569.

The first and most famous "projection" of a spherical globe onto a flat map, giving sailors accurate lines of longitude and latitude.
14. A map showing the most popular sports around the world.

15. The Ortelius World Map (1564), the first map by Abraham Ortelius, creator of the first modern atlas.

The Theatrum Orbis Terrarum, published in 1570, was a collection of 53 maps.
16. A map showing countries by number of internet users.

17. A map of the most popular website in each country.

By the data nerds at webempires.org.
18. A map showing the results of a survey asking the world who they see as the biggest threat to world peace.

People are pretty scared of America, it turns out.
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