The Christian wall started its construction just after the conquest of the city by King Alfonso VI, and it was concluded in 1150. It was 2,2 kilometers long and included 140 defensive towers of 10-15 meters each.
The wall was built of flint stone which produced sparks when hit. For this reason the city slogan is: "I was built on water; my wall is made of fire"
There were four gates: Guadalajara, Balnadú, and Moros in the south; and Cerrada, firstly known as the Gate of the Snake because of the snake depicted on it. Locals started to call it the Closed Gate due to the fact that it was kept closed to prevent against rampant crime.