If you use 3D objects for making an environment for your scene you definitely need 3D models of buildings.
There are a lot of free and paid stock 3D models you can use in your project.
Let me share a link to the good free 3D model of the set of buildings that are appropriate for environments of architectural or maybe, other kinds of scenes.
The reasons why this 3D model is good are the following:
1. It's free.
2. It's compatible with 3DS Max 2011 and newer and V-Ray which are one of the most spread software combinations.
3. The package also has .fbx file with V-Ray materials you can use in software that supports this format.
4. The geometry and materials are done well. Though you can edit the materials if you need to modify.
5. Four various buildings are done in one style. So it's a good option to use them with other 3d models of buildings to achieve variety.
About the Author
Yevhen (Ievgen) Zakharov is a 3D Visualizer Artist from Ukraine, who did more than a thousand 3D Renderings including Architectural, visualizations since the year 2001. Feel free to learn more about him and his team.