A method and system generates a building design and a three-dimensional image thereof. First building information comprising a length, width, total height and wall height of a building is received via a first graphical user interface. If the length, width, total height, wall height, and a selectable building shape yield a valid set of building parameters, a design of said building is generated at a first software module, which is configured to generate the design, including wall portions and a roof portion, using minimum information consisting of the length, width, total height, wall height, and selectable building shape. A first image and a structural analysis of the design are generated. A second software module generates a second three-dimensional image of the building, which is different from the first image. A second graphical user interface permits a user to modify the second image to include predefined building elements.