The EU's ambition to achieve climate neutrality by 2050 and increase networks interconnection, makes the proliferation of hybrid AC/DC grids a promising solution towards a more interoperable and resilient pan-European system. In this context, THEUS project aims to showcase advanced methodologies and tools supporting hybrid grids implementation across High Voltage (HV), Medium Voltage (MV), and Low Voltage (LV) levels. To successfully achieve its objectives, the project will develop a set of six planning and six operation solutions, that will be validated in five use cases addressing the most representative challenges faced by European grids. These use cases will rely on accurate models and will be fed with data from five real grids representing different project stages and voltage levels: a planned transnational HVAC/HVDC transmission interconnector connecting Crete-Cyprus-Israel; an existing distribution hybrid grid in Italy; a planned MVDC distribution grid in Turkey; an existing HVAC/HVDC link between Attica-Crete; an existing MVAC/MVDC/LVDC microgrid in Spain. The validation will be conducted on six test benches that will allow to reach TRL 5 by the end of the project. THEUS assembles a competitive consortium of 15 partners from 8 EU countries, including research organizations, technology manufacturers, electric system operators, a wind farm operator, a SME to guarantee the exploitation of the project solutions, and a European Association to ensure the successful dissemination of the project outcomes. THEUS will directly impact in the electricity system orchestration of future pan-European AC/DC hybrid architecture by performing a validation campaign in which 2 under-planning networks will be designed, and 3 existing networks will be improved in terms of management and operation. Overall, THEUS is expected to achieve 10-30% reductions in energy losses and 15-20% in O&M costs while ensuring the safe operation of hybrid grids with a higher penetration of RES.