Although you can use CityGen3D just as a terrain and landscape generator, there are also various tools available to make urban environments.
The roadside object spawner is a quick way of filling out your scene because it can instantiate lots of prefabs that are automatically placed around roads.
These prefabs can be anything you like, such as houses and street lights.
You are able to limit certain prefabs to specific surface types. For instance, to ensure homes are only instantiated in residential areas and shops are generated in commercial areas.
Later in the beta phase, CityGen3D will also have BuildR2 compatibility for generating buildings based off OSM map data.
This will allow you to automatically generate realistic representations of real world buildings, before filling out your scene with roadside prefabs.
Here you can see a test showing how Millbank Tower in London was generated by CityGen3D from map data using the work-in-progress BuildR2 integration.