Le Grand Paris en Cartes is a collection of interactive maps and infographics about the Grand Paris Express, a multi-billion-euro project to extend Paris’s Metro and rapid transit network deep into the surrounding Île-de-France region (if you can read French, the official site and French Wikipedia page provide a lot more information). These maps not only illustrate Parisians’ commuting routes and Metro usage, but also (see above) the kind of sociological data that underpins transit planning: employment centres, population density and so forth. In French. [via]