This is MEL script I built for Autodesk Maya several years ago that can quickly generate a “downtown” cityscape in a few minutes via a basic GUI.
Feel free to see more information (and to download the script for your own use) at this blog post.
NOTE: This was a only meant to be a quick way to create a cityscape; so if you want more advanced materials or textures you will have to add them yourself. Please feel free to play with and modify the script as you like! As a heads up, though, I have the city objects layers locked so they aren’t selected when selecting the plane to create buildings.