11 Borders and edges are salient and behaviourally relevant features for navigating the 12 environment. The brain forms dedicated neural representations of environmental 13 boundaries, which are assumed to serve as a reference for spatial coding. Here we 14 expand this border coding network to include the retrosplenial cortex (RSC) in which 15 we identified neurons that increase their firing near all boundaries of an arena. RSC 16 border cells specifically encode walls, but not objects, and maintain their tuning in the 17 absence of direct sensory detection. Unlike border cells in the medial entorhinal 18 cortex (MEC), RSC border cells are sensitive to the animal's direction to nearby walls 19 located contralateral to the recorded hemisphere. Pharmacogenetic inactivation of 20 MEC led to a disruption of RSC border coding, but not vice versa, indicating network 21 directionality. Together these data shed light on how information about distance and 22direction of boundaries is generated in the brain for guiding navigation behaviour. 23