Computer based visualization tools have the capacity to create convincing reconstructions of historical structures that appear to be authentic and complete but where inferences have been drawn from relatively limited evidence. The challenge is how to make the exciting process of discovery, argument and reasoning more self-evident in the model and also make known the alternative constructions that were plausible but less likely. This paper refers to two computer visualizations developed by the author for world heritage building sites. In both cases, a similar geometrical modeling technique was used. However, in the second case, the 3D modeling approach is developed for juxtaposition with captured dialogs, the evidence used, and the process followed so as to make level of speculation more explicit.