Some of the most famous cities in history were never built. These 10 Utopian cities may have been failures, but they expressed our ideas about what the future of human civilization could look like. And many ideas contained in them continue to influence us today.  Some pictures and details of these visionary cities can be found here:

http://io9.com/10-failed-utopian-cities-that-influenced-the-future-1511695279