The city is one of the most important fortified precincts in the world. They are considered as the most complete construction from the Middle Ages.

They were started by Raimundo de Borgoña. It approximately has 2500 meters of perimeter, with 88 towers and large fortified towers. The average high of the wall is 12 meters. The design is an irregular rectangle and it is fortified with towers and cubes crowned by merlons. They are well conserved due to its restorations. The monumental gates of the Alcázar and San Vicente are flanked by towers that are more than 20 meters high. In the wall is inlayed the apse of the Cathedral, with a semicircular tower much bigger than the rest of towers, it is called the Cimorro.

The walls were built in order to control the entrance of provisions, the entrance of merchandise, and to isolate the city from possible plagues and epidemics, including its defensive function.