Here are a few structures I built for my N scale model railroad; these are mostly constructed from cardstock using balsa wood for trim and acetate for windows. They're colored with felt tip marker, colored pencil and chalk.
The two buildings are just sitting on the layout for now. They haven't been secured to the ground and landscaped.
The entire layout is 3' X 4' in size and contains one switch; I kept it simple so I could concentrate on the modeling aspect.
Railroad station at Inman, Kansas
Rimerton house in ?, Pennsylvania
Some related links:
Atlas
Lionel
Marklin
Model Railroader
Magazine