Under the supervision of Pere Balaguer, construction began in 1392. The towers were designed to be defensive structures at one of the busiest city gates. They were saved from demolition when the city walls were knocked down in 1865 and used as a prison for the nobility between 1586 and 1887. The back of the towers have been opened so that the pointed arches and the vaulted domes can now be seen from the Plaza de los Fueros. The Towers represent an excellent example of gothic architecture.