This presentation gives an overview of the design of district-level multi-energy systems and relevant key performance indicators capable of providing flexibility to the power system to enhance the grid operation. The proposed data-driven "District to Grid" approach evaluates major energy options at building levels, and delves into the evolution of the energy distribution, storage, behavioral flexibility and alternative pricing to avoid carbon emissions and increase the self-consumption at the scale of the neighborhoods. The methods are illustrated with case studies addressing decentralized and centralized investment planning options for the energy transition.