Numerous catastrophic wildfires in Greece have demonstrated that relying on fire suppression as the primary risk-management strategy is inadequate and that existing wildfire-risk governance needs to be re-examined. In this research, we used simulation modelling to assess the spatial scale of wildfire exposure to communities and cultural monuments in Chalkidiki, Greece. The study area typifies many areas in Greece in terms of fire regimes, ownership patterns and fire-risk mitigation. Fire-transmission networks were built to quantify connectivity among land tenures and populated places. We found that agricultural and unmanaged wildlands are key land categories that transmit fire exposure to other land tenures. In addition, fires ignited within protected lands and community boundaries are major sources of structure exposure. Important cultural monuments in the study area had fairly low exposure but higher potential for fires with moderate to high intensity. The results show how the spatial diversity of vegetation and fuels, in combination with vegetation management practices on private and public tracts of land, contribute to transboundary risk. We use the results to motivate a discussion of integrating transboundary risk assessments to improve the current wildfire-risk rating system and begin the process of reforming risk governance in Greece.