This paper describes an experiment which investigates the possibility that stone circles were laid out by eye rather than being geometrically planned. Over 100 simulated stone circles were built and hence a data set of known layout method was generated for comparison with ancient stone circles. The results illustrate that no distinction can be made between the hypotheses. Examination of other architectural traits and geographical distributions suggest, however, that simple laying out procedures, as opposed to the more complex geometries proposed by Thom, are more appropriate for stone circles in Britain. -- AATA