1:150 Scale Architectural Models (6.6mm represents 1 metre) This is a good scale option for showing a high level of detail whilst keeping the model at a compact size. It works well for individual buildings, small housing developments or groups of apartment blocks, as you'll see from the photos on this page.
If the purpose of the model is to show just the building itself you could consider 1:200 or even 1:100 scale. At these scales you can show windows, doors, balconies, etc.
An architectural model is a type of scale model made to study aspects of an architectural design or to communicate design intent. They are made using a variety of materials including paper, plaster, plastic, resin, wood, glass, and metal.