The ARTEMIS project (Applying Reactive Twins to Enhance Monument Information Systems) aims to revolutionise cultural heritage research and preservation by leveraging the concept of Reactive Heritage Digital Twins (RHDT). Deliverable D1.1, the Data Management Plan (DMP), outlines the foundational principles, practices, and resources dedicated to managing the project’s data throughout its lifecycle. This initial version of the DMP serves as a living document, providing a strategic framework for the handling of datasets reused, processed, or generated within ARTEMIS. While the project does not create new primary research data, it aggregates, enriches, and makes accessible a vast array of existing datasets from prominent heritage repositories such as ARIADNE RI, HSDS, KIK-IRPA, and LNEC. The primary output of ARTEMIS will be metadata and pilot implementation frameworks based on RHDT. The DMP emphasises adherence to FAIR principles, ensuring data is Findable, Accessible, Interoperable, and Reusable. It describes the mechanisms for persistent identifiers, metadata standards (including RHDTO, CIDOC CRM, and Getty AAT), and the creation of a Knowledge Base that enables semantic and user-friendly access to cultural heritage data. Data accessibility is ensured via trusted repositories like Zenodo, GitHub, and DARIAH-Campus, with all outputs shared under open licenses (CC BY or CC0). The plan addresses data security, ethical considerations, and GDPR compliance, particularly in handling personal data for project activities such as surveys, training, and event participation. It also ensures long-term preservation of project outputs, underlining sustainability and public availability beyond the project’s conclusion. Resources for data management, including technical infrastructure and personnel, are embedded into the project’s operational budget. Governance responsibilities are distributed across Work Packages, with the Scientific Coordinator overseeing updates and compliance. In conclusion, this DMP reflects ARTEMIS commitment to Open Science, collaborative innovation, and responsible data stewardship. It lays the groundwork for transparent, scalable, and ethically sound data management practices that support the long-term impact of the ARTEMIS initiative on cultural heritage research across Europe.