This paper is based on the 2012 Europa Lecture and discusses the relationship between the forms and structures of domestic buildings and those of public monuments. Its chronological scope extends between the Neolithic period and the Viking Age in western, northern and central Europe, with a special emphasis on the contrast between circular and rectilinear architecture. There were practical limits to the diameters of circular constructions, and beyond that point they might be organised in groups, or their characteristic outlines were reproduced in other media, such as earthwork building. By contrast, the main constraint on building rectangular houses was their width, but they could extend to almost any length. That may be one reason why they only occasionally provided the prototype for specialised forms of monument such as mounds or enclosures. Instead rectangular buildings played a wide variety of roles from domestic dwellings to ceremonial centres.