Cultural heritage assets are vulnerable to deterioration due to environmental and anthropogenic factors. Preventive conservation proactively safeguards assets through early detection of harmful environmental factors like light, temperature, humidity, and pollution. However, traditional conservation methods often suffer from limited data, inefficient monitoring, and resource constraints. This paper presents SENNSE, an IoT platform designed to enhance the monitoring, and preservation of cultural heritage. SENNSE integrates real-time data from wireless sensors and data loggers into a dynamic digital twin—a 3D, spatially accurate, and interactive model of the heritage site accessible via VR. This immersive environment enables remote users to explore sensor data and initiate actions through holistic VR experience. IoT sensors provide real-time responsiveness, while data loggers cover areas with network, power, or aesthetic constraints. SENNSE’s architecture includes an MQTT broker for bidirectional data transmission, cloud-based analytics for storage and interpretation, and an interactive application layer for visualisation. A case study of the Grotta degli Animali at Villa di Castello in Florence, Italy demonstrates SENNSE’s capability to support data-driven, site-specific conservation planning. This interdisciplinary approach bridges technological innovation and cultural preservation, offering a scalable, modular solution adaptable to diverse heritage contexts. By creating a digital twin enriched with real-time environmental data, SENNSE contributes to sustainable conservation practices and the long-term protection of cultural legacies.