The first set of walls built in Porto surrounded the Morro da Sé, in the high area of Pena Ventosa, which was of significant and strategic importance for the control of the Douro passage. Only a few small sections survive, and some are partly concealed by houses. It is thought that some of the sections were built by the Romans and others were rebuilt in the twelfth century. This wall had four gates or entrances.
Nowadays, it's possible to see a small portion near the Sé Cathedral that is clearly marked. In the fourteenth century, with the development of the city, the old city wall was replaced by the Fernandina wall. King D. Afonso IV ordered the construction of the new wall, which had a length of 4500 meters and a height of 10 meters tall. Currently, one can only see the Santa Clara section and the stretch by S. João Novo. The Fernandina Wall is the one that follows the path of the Funicular dos Guindais.