A system, a method and a computer program, including an online application software, that enable any user to input the address of a property site at any geographical location worldwide, where the user desires to erect a new building. The system includes a plurality of modules, including modules for residential, commercial and civic buildings in all community types, and through a series of steps guides a user along the process of assessing and determining the allowed buildable envelope, selecting desired building type, building program, construction system, architectural style, and level of environmental responsiveness, as well as intended construction budget. The system analyzes these data and produces building designs that comply with all local, state / provincial and federal / national applicable codes and regulations, embody a rigorous set of architectural, engineering and construction best practices and know-how, related to the specifics of the project, and best respond to the site constraints and user criteria.