Tate Modern's current exhibition, titled Global Cities, makes artwork out of population density statistics of twelve of the world's largest cities:
Overcrowding never looked so attractive. As part of the Tate Modern’s current exhibition, Global Cities, on display in the gallery’s vast Turbine Hall, is a series of intriguing “density models”. The plywood structures were created by a team of designers and architects at the London School Of Economics, led by Professor Richard Burdett. The models are shaped around the outlines of each city, with each layer of plywood representing an extra 200 people per square kilometre.
http://www.creativereview.co.uk/crblog/global-cities-at-tate-modern/ | Global Cities official website - Thanks Patrick Burgoyne!