Mura della Marina marked the limit between the city and the sea. Built in the 12th century, they were repeatedly redeveloped until they found their final shape in 1630, within the New Walls. A good stretch of them ran where we now admire the colourful palazzata from Sarzano towards Campopisano, once lapped by the sea.
With the building of the ring road to the sea, the Walls lost their function as a bastion and became a simple containing wall.