City Walls and Urban Enclosures

Before being a network of streets, the medieval town was a boundary. “To make a town” meant, in the language of the time, demarcating a space and enclosing it with a wall—and it was this ring of stone that distinguished the settlement with its own rights from the open countryside around it. The urban enclosure is, therefore, one of the most revealing typologies of Portuguese built heritage: in it, one can read, layered, the defense, the legal status, and the form of the city.

From the Old Enclosure to the New Enclosure

Walled perimeters were not always built from scratch. Many settlements reused late Roman walls—the so-called old enclosure—or enclosures of Islamic origin, such as the medina and the suburb that structure the old quarters of many southern cities. Upon this heritage, the first properly medieval enclosures were erected in the 12th and 13th centuries, as the Reconquista settled populations in new towns.

The great leap came later. With urban growth in the 14th and 15th centuries, the suburbs overflowed the ancient walls, leaving convents, workshops, and people outside them. The insecurity of the border with Castile—particularly during the reign of King Fernando— triggered a movement to build new enclosures that encompassed these suburbs, sometimes including empty land as a reserve for future growth. Lisbon, Porto, and Évora thus girded themselves with a second ring.

The Fernandine Enclosure of Lisbon, built between 1373 and 1375 to replace the old Roman wall, featured about 77 towers and over thirty gates and posterns—a project completed in just two years, in response to the Castilian threat.

The Grammar of the Wall

Every urban enclosure is organized according to a common vocabulary, shared with the medieval castle and the rest of Portugal’s military architecture. The wall curtain is topped by merlons and arrow slits, traversed inside by the wall walk, the patrol path that allowed movement along the defense. At regular intervals, towers—square or semicircular—projected from the curtain and covered the base of the wall.

The sensitive point was always the gate. Often crowned by a tower and protected by a bent corridor, the gate concentrated defense and, simultaneously, regulated the entry of people and goods, where tolls were collected. The posterns, more discreet, served as secondary passages. When artillery became dominant, a second, lower belt was added in front of the wall, the barbican, designed to absorb the impact of fire.

Stone Memory in the Urban Landscape

Few circuits have survived intact to our days: urban growth, the loss of military function, and the opening of new avenues led to the demolition of entire sections as early as the 19th century. But the design of the enclosure survived in another way—in the curved layout of streets that follow the ancient perimeter, in the names of long-vanished gates, in sections embedded between buildings.

Where the wall has endured, it still defines the silhouette of the place. Óbidos offers the most complete example, with its walkable circuit crowning the town; Évora, Coimbra, Bragança, Trancoso, Barcelos, and Ponte de Lima preserve gates and sections of great quality. This typology closely intersects with fortified towns, where enclosure and settlement merge, and with towers and watchtowers that monitored the territory beyond the walls.