At the core of any computational system that can support design development, analysis, and evaluation is an “intelligent” building representation which should be able to represent all the different components that make up a building, along with the manner in which they come together. In other words, the representation must be informationally complete and semantically rich. The paper discusses these two criteria and briefly reviews other research efforts aimed at developing building representations for computer-aided design that attempt to meet them. Our solution to this problem is then presented. It is aimed primarily at the schematic design phase, the rationale for which is also stated. Taking the view that buildings are unique assemblies of discrete, mostly standardized components, our representation is clearly divided into two components: the Object Database (ODB) which stores detailed information about various building elements, and the Project Database (PDB) which holds information about how these elements are assembled to make up a particular building. An ODB may be shared by many building projects, while the PDB must necessarily be unique to each. The data schemas of both the PDB and the ODB are described in detail and their computational implementation, to the extent that it has been completed, is illustrated.