This is a collaborative research project funded by the Spanish Research Agency (AEI) for synthetizing functional complex carbon-based molecular nanostructures with atomic precision and testing their potential operability as functional units in various technological applications, such as spintronics, topological engineering, (opto)electronics, thermoelectricity, and chemical and molecular sensing and filtering. FunMolSys combines the work of six Spanish research groups in Galicia (CiQUS at the University of Santiago de Compostela), Euskadi (the CFM, Centro de Física de Materiales - CSIC-UPV, and CIC nanoGUNE), Aragón (the ICMA, Instituto de Ciencia de Materiales de Aragón – CSIC-UZ), and Catalunya (the ICN2, Instituto Catalán de Nanociencia y Nanotecnología). In the last years, FunMolSys has produced novel strategies for synthesis of customized graphene platforms over metallic surfaces and identification of their new electronic and magnetic properties with a combination of multiple experimental methods, theoretical tools, and multidisciplinary expertise. Within FulMolSys, the research groups of Theory and nanoimaging, led by Profs. Artacho and Pascual, respectively, contributed with a sub-project entitled “Magnetism and topological states of on-surface engineered molecular nanosystems”