Piers are the ultimate interface between land and water. They are the connection between port cities and the planet. Their accessibility has been a key indicator for the evolution of the port-city relationship. They changed from being accessible in the past, to gradually becoming off-limits. Fortunately, there is an ongoing tendency to reopen the piers, establishing a new kind of port-city relationship. How permeable are these relationships today? What flows are shaping these interactions? How are port cities presenting local answers to global trends? How do they fit together? And how are ports reopening their piers?