Check it out: This site shows the subway systems of the world, presented on the same scale — so you can see how each city compares to each other directly. That’s Paris above. Moscow is this totally immense sprawl, and Barcelona looks like a ton of fun; it’s really comprehensive but teensy, so you get the sense that there’s a subway stop every 30 feet or so. My only complaint is that they didn’t include the Toronto and Montreal subway systems, two of my world favorites.

Of course, I have now just admitted, in print, that I actually sit around thinking about what my favorite subway systems are.

(Thanks to Boing Boing for this one!)