SketchUp:

Architecture and City Planning

SketchUp is a parametric CAD program which can be used for woodworking, 3D printing, and  architectural design, and city planning. Users have access to an extensive '3D warehouse' of pre-designed components, trees, and other items that can be added to designs.

The web-based version of SketchUp is free; there are also paid desktop versions for professionals.

SketchUp for City Planning: