The main function of the Porticciolo della Marina of Piombino, located at the seaport (no longer existing), was that of serving the city. In 1247 it was embellished by the Fountain of the Marina, or Fountain of the Canals (also called "Snakes in love" for its bar-relief depicting two serpents), extremely important for providing drinking water to the population and to ships. In the second half of the 15th century the Porticciolo was reorganised on a rational basis at the order of Jacopo III. In 1465 a wharf was built to hold a galley at the disposal of the Lord of the city, along with other small mercantile ships. In 1471, to provide better defence of the small landing place, it was decided to build a tower, no longer existing today. During his visit in 1504, Leonardo da Vinci became interested in the situation of the Porticciolo area, judging it to be the only weak point along the coast, since it had no suitable defensive works. In Madrid Ms. II (Manuscript "8936", now in the National Library of Madrid) can be found, in fact, a drawing in which Leonardo depicts a real urban port having a fortified bastion with a defence tower, which was to have taken the place of the Porticciolo. Remodelled several times over the centuries, the ancient wharf is today a characteristic landing place for boats engaged in for the traditional activity of fishing.