Planning is made up of borders.As social and political constructs, a border divides be it landscapes, communities or ideas and legitimises particular policy activities or approaches.Within urban and regional planning contexts, borders become elements of control, as they shape and define how particular territorial issues, spaces and places are understood and acted upon by communities of interest.In this paper, we focus on borders and re-bordering processes as a potentially transformative agenda for urban planners.We join with Paasi (2011) to ask in whose interests are particular borders created and by whom? Through the lens of the border, seemingly rigid or entrenched urban borderlines can be made more visible, unsettled and/or disrupted in key areas, such as urban consolidation, critical infrastructure and urban ecology.