CASTIEL´s mission is to contribute to the success of the activities of the National Competence Centres (as realized in the Research and Innovation Action (RIA) in the same call – EuroHPC-04-2019 by tackling both the maintenance and strengthening of excellence, while identifying and closing gaps due to the diverse levels of maturity between the different nations. CASTIEL will therefore bring together a core consortium to setup a framework of activities that will support the evolution of each single National Competence Centre and enable them step by step to get closer together in terms of capabilities and expertise. The greatest challenge hereby is the integration of the single nations into the overall strategy at European level while preserving their autonomy and without interfering with their national strategy. This will address, the challenge of maximising existing European HPC knowledge and expertise across Europe, and CASTIEL will take the role of a single and central reference point at European Level to coordinate and support the National Competence Centres.