Housed in Drassanes, the Gothic shipyard of the city. During the 14th century, the Arag Crown was the most important power in the Mediterranean Sea, and this was the main place where the ships were built. Nowadays, it's the Maritime Museum, worth a visit for the architectonic structure, a still-standing part of the ancient medieval city wall (including a gate), and the reproduction of the royal galley of Don John of Austria. This was the Spanish flagship at the battle of Lepanto. If you do not want to go inside the museum, you can see a little bit looking inside through the big windows at the part in front of the sea.