The city plan, which became fixed in principle during the16th century, developed in a radial fashion around the summit of the hill. At the limit of the old centre, which had an irregular layout, some of the city squares (Giraldo and the Moura Gate) provided points of departure for the urban axes that gave structure to the ensemble and extended out into the region. Between these axes, the urban area is crowded by networks of narrow streets, most often in a straight line, with varied orientation from one ensemble to another. Three successive fortifications (Roman, medieval and Vauban) enclosed the city.

Among the walls and the vestiges of walls, which are bordered with gardens, low white dwellings with tile roofs (or a terrace) ensure a unified architectural ensemble; this is enhanced by cast ironwork and azulejos. Numerous palaces and convents (constructed of granite in certain cases) of Manueline inspiration date to the 15th century. The 16th century, however, witnessed the construction of great works of architecture and urban planning, such as the aqueduct which dates to 1537 and numerous fountains.