Photoshop. All stock from sxc.hu.
3DStudio 7, ambient light and one semitransparent material with a falloff refraction map. Rendered with mental ray DOF. Print’s image size: 7200 X 4800. Rendering time 56 hours, 14 minutes, 38 seconds (On a very old laptop)
Originally posted on my DA. Look here for links to source photos: https://robertllynch.deviantart.com/art/Future-City-56721236