The progressive re-engineering of the European power transmission system will involve a spectrum of innovative technologies. Their level of application by Transmission System Operators (TSOs) will vary from one control area to the other, also based on past experiences and today's operation constraints. The present paper introduces a Technology Integration Roadmap, developed within the European research project REALISEGRID, with the aim to analyze the evolution of advanced transmission technologies over the next three decades towards their integration into the European power system. This roadmap is based upon a systemic approach which takes into due account two knowledge elements: the transmission system perspective and the technological perspective. It is organized into high level technology components based on a common long-term vision of the European electricity network by 2030, the critical system challenges driving that vision and the overall benefits expected from the implementation of this spectrum of technologies. The present paper proposes an Action Agenda for the next three decades, with potential integration trajectories including milestones as seen by TSOs and manufacturers respectively.