Cities are the major source of European economic activity and innovation. But cities are also a major source of greenhouse gases and pollution. Concerted action is needed to make urban environments cleaner and healthier to live in and to make them use less energy. The European Innovation Partnership (EIP) on Smart Cities and Communities and its "Strategic Implementation Plan" are leading the way in making the transformation of cities into "Smart Cities" a reality. Real impact could be made through investments in 'zero/plus' energy districts, increased use of alternative energies for cleaner transport, public transport and efficient logistics to reduce negative impacts of congestion, or green, widely available ICTs and multiple-use infrastructures.