Evey project I work on is different so a generic background model would be very difficult to achieve.
Are you wanting high levels of detail or just massing models?
You could use pre made buildings such as the ones here at FormFonts (subscription required)
http://www.formfonts.com/search.php?area=Models&query=buildings
It is possible to create a photomontage by placing your model into a photgraph of the surrounding area.
There are many ways but we would need more specific details to give better information.