A new type of area of interest (AOI) termed “choice zones” is proposed, that is relevant for eye tracking research in the built environment. Choice zones are an ex ante measure; this is in contrast to many existing definitions of AOIs which are data-driven. Choice zones are defined algorithmically using space-geometric parameters. The validity of the concept is tested against fixation data from an urban navigation experiment in which participants chose between alternative paths. Findings show that choice zones account for 90% of the fixations clusters. The merit of the measure for applied studies in built environment research is discussed.