In the context of architectural and urban design, we compared and contrasted passive observation of walkthroughs of a desktop computer modelled environment with user-controlled (active) navigation of the same model. In a study involving 81 participants, we explored the differences in subjective responses attributable to navigation mode. Quantitative measurements using perception and sensation scales showed that differences were relatively minor, but generally suggestive of a positive connotation for the active condition. Notably, we also observed differences in the way self-navigators and observers speak about and recall the environment they experienced. These differences lead us to conclude that the best mode of presentation of a virtual built environment depends on the purpose for which opinion is being sought.