Port Cities can be seen as multidimensional laboratories where challenges connected with urban mobility are more complex due to the dual system of gravity centre: the city, the port, not to mention their shared hinterland.These peculiarities are at once a challenge and an opportunity, as they provide scope for planning, researching and implementing integrated mobility solutions in distinctively complex urban contexts. Civitas PORTIS designs, demonstrates and evaluates integrated sets of sustainable mobility measures in 5 major port cities located on the North Sea (Aberdeen and Antwerp), the Mediterranean Sea (Trieste), the Black Sea (Constanta), and Baltic Sea (Klaipeda). The project also involves a major international follower port city on the East China Sea (Ningbo). Thanks to the Civitas Initiative, the partner cities expect to prove that more efficient and sustainable mobility is conducive to the establishment of vital and multi-modal hubs for urban, regional, national and International movements of passengers and goods. To do this, they establish integrated living laboratories clustering local measures according to four major aspects of sustainable urban mobility: 1. Governance: to increase port-city collaborative planning and participation, leading to enhanced forms of SUMPs. 2. People: to foster less car-dependent mobility styles, leading to modal shift in favour of collective and more active transport. 3. Transport system: to strengthen the efficiency of road traffic management to/from the port and through the city, and foster the use of clean vehicles. 4. Goods: to enhance logistics and freight transport, improving the efficiency and coordination of city, port and regional freight movements. Working with port cities, Civitas PORTIS will generate a strong and twofold replication potential: 1) specifically to other port cities, and 2) more generally to cities presenting major transport nodes and attractors for the benefit of the whole CIVITAS Initiative.