The ARTEMIS proposal addresses the field of cultural heritage conservation, restoration, safeguard and valorisation by advanced digital technologies, using digital twins and relying on advanced AR/VR technologies. It relies on an extended digital documentation of heritage assets with 3D models incorporated in their digital twins, by implementing services on heritage data that model the behaviour of the real-world assets in different conditions and under the effect of complex external phenomena. The same approach will allow digital experiments testing the effect of activities simulated on the twin. Whenever suitable, the developed services will avail of AR/VR techniques to manage the simulation input and to visualize the outcomes. ARTEMIS will rely on the know-how of participating world-class research infrastructures, making available a huge amount of heritage documentation data, on the contribution of advanced research centres and on the support of specialized technological SMEs. The project will produce a scientific methodology tested on a large number of pilots and will pave the way for innovative applications in heritage research based on digital twins and AR/VR techniques.