The maps Twitter NYC [] and Twitter Tongues [] depict the cities of New York and London respectively according to the languages of the Twitter messages that were broadcasted within their territories.

The New York map, developed by James Cheshire, Ed Manley and John Barratt, is based on about 8.5 million geo-located tweets captured between January 2010 and February 2013. Both cities being major tourist attractions, the resulting maps are actually a combination of the latent language distribution and density of the local population, as well as that from the international tourists.

Via FastCoDesign. More information als available here and here. Details on the data processing here.

See also:
. NYTimes Maps U.S. Census Data in Every City Block
. The World Mapped According to Wikipedia Articles in 7 Different Languages