Among SDM solutions, Multicore Fibre (MCF) enables multiple spatial channels within a single optical fibre, significantly increasing transmission capacity. By integrating a state-of-the-art multicore fibre testbed into Lisbon’s underground metro infrastructure, LUMIRing bridges the gap between laboratory research and operational networks. To achieve this, LUMIRing deployed an experimental MCF testbed along the Yellow Line of the Lisbon Underground (Metropolitano de Lisboa). It provides students, researchers, and engineers with hands-on access to a world-class MCF testbed, helping develop expertise in SDM networks. By providing a unique real-world testbed, LUMIRing enables external partners to validate and demonstrate new technologies under operational conditions.