This paper presents the argument that navigational ease has a greater impact on building usability compared to other factors, hence it subsumes other usability considerations. Patterns of human behaviour inside buildings can be held to consist of two types, static occupancy and dynamic movement and need to be readily accessible to both regular users as well as infrequent/first time visitors. Furthermore it is the circulation system of a building that facilitates a high proportion of informal, unprogrammed social interactions that contribute to the social life of a building.This paper will highlight a number of design moves/considerations that appear to either aid or conversely hinder navigability through a series of case studies. The case studies described in this paper primarily include the Heinrich-Luebke-Haus in Guenne (a 1960/70s conference centre in NW Germany), the Kollegiengebaeude I (a picturesque, Jugendstil campus building of the University of Freiburg unsuccessfully fused to an adjacent 1970s addition, located in SW Germany) and The Seattle Public Library (by OMA with LMN Architects, 2004, located in Seattle USA). Through these case studies, the authors will illustrate how certain design guidelines (for example, the use of straighter, more direct routes (Conroy Dalton 2003); unimpeded lines of sight connecting key building spaces (such as entrances, atria, stairs, lifts and escalators) (Gaerling et al, 1986); the avoidance of abrupt changes of direction in corridors; ensuring that differences in floor layout between floors are not significant (Hoelscher et al, 2009); the avoidance of excessive spatial complexity and locations bearing a strong visual similarity to other locations (Weisman, 1981)) can have a strong effect upon navigability. Evidence for these guidelines is demonstrated through studies conducted in the above-mentioned buildings.The methods employed by the authors in these case studies include visual and spatial analysis (space syntax analysis (Hillier 1996)), the use of experimental methods (wayfinding tasks, think aloud protocols, pointing tasks, eye-tracking (mobile and on-screen), memory recall tasks and direct observation), social science methods (self-reporting questionnaires, interviews), simulation methods (virtual reality simulations of both actual buildings and alternative design-solutions of existing buildings and agent-navigation simulations), problem analysis and redesign tasks (architect’s redesign tasks/interviews), a focus on signage (sign and signage-placement analysis and signage re-design alternatives) and standard psychological spatial ability tests (for example mental rotation tests).The evidence from this considerable corpus of work presents a compelling case for the importance of ease of navigation for a building user. It is finally argued that whilst other aspects of a building’s usability may be tolerated, a dysfunctional circulation system rapidly leads to widespread user frustration.