This paper presents an experiment on judgments of design complexity, based on two modes of stimuli: the layouts of corridor systems in buildings shown in plan view and movies of simulated walkthroughs. Randomly selected stimuli were pre-sented to 166 subjects: 'experts' (architects or students currently enrolled on an architectural course) and 'lay people' (all others). The aims were to investigate whether there were differences between these two groups in terms of their judgments of building complexity, effects of modality of stimuli and if any environ-mental measures (geometric or complexity-based) correlated with the assessments. The results indicate that indeed complexity and wayfinding ratings show distinct patterns. Architects are more sensitive to differences between complexity and wayfinding ratings in the plan views, while lay-people provided more distinctive ratings for movies. Similarly, lay-people judged the same materials to be simpler and easier when seen as ego-centric movies, with architects showing the opposite pattern. The judgments of both groups correlated highly with a number of envi-ronmental measures, with architects providing greater differentiation regarding layout symmetry.