Remote built heritage sites face increasingly complex threats from climate, environment, and human activity, challenging traditional preservation methods. The ARGUS EU project introduces a novel, sensor-driven strategy for preventive preservation, tailored to remote and infrastructure-poor heritage contexts. This paper presents the threat-to-sensor mapping framework developed in ARGUS, aligning sensor types with site-specific preservation risks. By combining heterogeneous sensing modalities, low-power communication protocols, and risk-informed design, the system supports actionable early warnings and long-term monitoring. Deployments across five pilot sites address key preservation threats: structural deformation, freeze–thaw cycles, environmental degradation, and biological growth. We describe the sensor selection rationale, installation strategies, and early operational insights across varied heritage contexts.