Architectural historians have compiled catalogues of actual buildings, with which—if drawings are included—it is possible to study the development of plans and built forms of different types over time. This paper will describe the production of catalogues of possible plans and forms for buildings, as constrained by the laws of geometry and topology, and by the demands of generic function. Generic function refers to those basic purposes that many buildings fulfill, such as providing natural lighting and ventilation, allowing access to all rooms, allowing the oversight of activities, and so on. Examples will include catalogues of small rectangular plans for houses; arrangements of apartments in slab blocks; circular and annular plans; and larger built forms made up of ranges, wings, and courts. The purpose is not to support the design process directly, but to contribute to an architectural science that can broaden knowledge of options in design. A second purpose is to allow an approach to architectural history in which the actual is set against the possible.(more)