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The European Community and its member states regularly invest large volumes of funding and effort in the development of HPC technologies in Europe. However, some observers express the criticism that these investments are either unfocused, lack long-term perspectives, or that their results are not mature enough to be adopted by the mainstream developments, which limits their benefit for the European HPC community, industry and society. This paper is intended as a counterexample to this pessimistic view. It describes the success story of Modular Supercomputing Architecture, which started in 2011 with the EU-funded R&D project “DEEP”, and is now being adopted by large-scale supercomputing centres across the old continent and worldwide. Main hardware and software characteristics of the architecture and some of the systems using it are described, complemented by a historical view of its development, the lessons learned in the process and future prospects.