The birth of Porto as a city dates back to the Roman period, to the 8th century B.C. , Celtic ruins have also been discovered in various areas. Over the time the city played an important role on the main trade route between Lisbon and Braga. At the time, the city was known as Cale, or Portus Cale (Port of Cale, the origins of the name of Portugal), and was situated on the banks of the Douro River where today Porto and Vila Nova de Gaia are located.
During the 13th Century, Porto exported the wine that was produced in the Douro by establishing relations in international markets. And it was at the end of that century, and during the next, that the export of Douro wines began to gain importance.
Blessed by the deep waters of the Douro River, Porto was crucial in the 14th and 15th centuries in the development of Portuguese shipbuilding and was the port from which in 1415 Henry the Navigator set sail to explore the western coast of Africa and initiating the Portuguese Age of Discovery. Under his command, the islands of Madeira and the Azores were reached in 1419 and 1427, respectively.
During that century, there was a huge increase in the population of the city, especially along the banks of the Douro River, due to the increasing importance of the trading and maritime activities. At that time, the settlement began to spread to beyond the boundary of the walls of the Porto Sé Cathedral, to the Old City Wall. In the middle of that century, the New City Wall began to be built, which also became known as the Fernandine Wall, as although it was begun during the times of D. Afonso IV, it was only concluded during the reign of D. Fernando.
During this century, the Porto shipyards were pioneers in the country´s naval development, thanks to Henry the Navigator.
During this time in the history of Porto, its people earned their nickname as "tripeiros", or tripe-eaters, the local population offered the sailors all the meat they had, keeping only the tripe to feed themselves.