Much work in software architecture has been inspired by work in physical architecture, in particular Alexander’s work on ‘design patterns’. By contrast, Alexander’s work is littleused in town planning and architecture. In this paper, we examine some of the reasons that this is so, describe some parallels and differences between the fields of physical and software architecture, and identify areas in which future collaboration may be fruitful. The notion of ‘participatory design’ is important in software engineering and in urban regeneration, but the participatory mechanisms in each field are quite different. Categories and Subject Descriptors D.2 [Software]: Software Engineering; D.2.10 [Software]: Software Engineering—Design; D.2.11 [Software]: Software Engineering—Software Architectures; K.4.2 [Computing Milieux]: Computers and Society—Social Issues General Terms Design, Human Factors Keywords Software architecture, participatory design, physical architecture