The observed width (and edge) dependence of the electronic structure and band gap of graphene nanoribbons has generated a vivid interest in the possibility to generate optically active, graphene-based quantum dots that can play a role in optically driven solid state devices for quantum information. We describe a bottom-up approach to generate armchair graphene nanoribbons (AGNRs) of well defined width and atomically perfect edges on Ag(111) surfaces under UHV conditions by debromination of DBTP precursors, covalent reaction along 1D metal-organic structures and subsequent covalent lateral reaction with neighbouring wires, giving rise to 6-12 AGNRs. The resulting graphene nanoribbons are examined in situ by STM and STS revealing the electronic structure of wires, heterojunctions and quantum dots at the atomic scale.