This innovative book documents border porosities that have developed and persisted between Greece and North Macedonia over different temporalities and at different localities. By drawing on geology's approaches to studying porosity, Dimova argues that similar to rocks and minerals that only appear solid and impermeable, seemingly impenetrable borders are inevitably traversed by different forms of passage. The rich ethnographic case studies, from the history of railroads in the southern Balkans, border town beauty tourism, child refugees during the Greek Civil War, mining and environmental activism, and the urban renovation project in Skopje, show that the political borders between states do not only restrict or regulate the movement of people and things, but are also always permeable in ways that exceed state governmentality.