"The Concentration City" is a dystopian short story by British author J. G. Ballard, first published, under the title "Build-Up", in New Worlds volume 19 number 55 in January 1957. It was reprinted in the collections Billennium and Chronopolis and later, under its revised title, in The Disaster Area and was also included in The Complete Short Stories of J. G. Ballard: Volume 1 and The Complete Stories of J.G. Ballard. Source: Wikipedia (en)