At the end of the Orion Arm of the Galaxy, there is a city: a crossroads of a dozen alien races, a home to dreamers, hustlers and runaways. A city waiting for your own stories and characters, at Orion's Edge.
Included are thirteen detailed .jpgs at 2500x2500 pixel resolution.
The Readme has a list of other 3d resources (most here at the Renderosity MP) that you can find and add to your SF scenes.