The big city is a sea of signs: we are surrounded by an exciting, pictographic labyrinth, whether in notices, posters, graffiti or advertising. Using digital cameras and GPS-receivers, teenagers and young adults have explored this semiotic realm, which invites a continual process of linking and association. Accompanied and encouraged by professional artists, they become authors of contemporary urban life. The emerging views of the European metropolises Barcelona, Berlin, London and Sofia are not only fascinating and often surprising; the four cities are interwoven using innovative possibilities of data processing to create an image of the European city that has never been seen before. In addition, Signs of the City: Metropolis Speaking shows the full range of this year-long project – workshops, the photo-community on the Internet, exhibitions and conferences – and introduces readers to the network comprising more than 30 institutions.