Spaces can be perceived as larger or smaller, according to how lighting affects the spatial boundaries. This is knowledge that can be used for changing the appearance of a desolate square or a cramped space. The following is a full-scale study of changing light scenarios that was conducted with 222 respondents in an urban space over five weeks. The study examines the effect of the spatial distribution of light and the placement of luminaires on our spatial understanding. A mixed methodology strategy, which combines pair-wise comparisons with qualitative interviews and a questionnaire, was used to examine the respondents’ perception of differences in spatial size and shape. The findings show that illuminated surfaces and objects, such as facades and trees, create a perception of increased or decreased depth, height and distance, depending on the spatial context and the respondent’s pre-understanding. Additionally, the perceived size of space was found to follow the height of the luminaires’ placement. This research study raises awareness of the impact of the placement of luminaires at varied heights, by developing the concept of light topography.