This paper describes the development of a software concept and a prototype system for a structured way of collecting and organising information about existing buildings. An analysis of traditional methods and processes involved in architectural surveying forms the basis for the development of a programming system for the structured surveying, preparation, organisation and use of digital information about existing architectural objects. Use is made throughout of current tools and techniques in the field of applied informatics, and these in turn are evaluated as to their suitability and usefulness. Particular emphasis is given to the systematic breakdown of a building into its component parts and information relevant to its use and planning, and to the integration of different methods of capture and presentation of this information. The architects'normal working methods inform the entire process.