Many of those articles are about places and people and events in human history, and some-at least four million-are tagged with the geographical coordinates of those places, people and events. Now, thanks to this awesome interactive map, you can explore the world's collection of digital knowledge one place at a time.

Several patterns jump out immediately when you load the English Wikipedia map. Some have obvious explanations. There are bright spots in many big cities. The area around Chicago is outlined in a near-perfect grid; from there, dotted lines follow the branching westward paths of interstate highways, and the towns built along them.

But the patterns also raise questions: Why, on a global scale, do the entries cluster the way they do? And what are the little points in the middle of the ocean about? (To find out, you can click on them for a link to the corresponding Wikipedia article.)

The interactive map allows you to plot Wikipedia posts in 12 languages, and the non-English language maps are at least as intriguing as the English one.