The aqueduct, typically the most recognized and famous symbol of Segovia, terminates at the entrance of the historic section. It was built at the end of the first to early third century BC by the Romans during their occupation of the Iberian Peninsula to bring water from the Frio River (about 18 kilometres away) to the city, requiring an elevated section in its last one kilometre from the Sierra de Guadarrama to the walls of the old town. This elevated section, largely dominating the nearby scene, is supported by an engineering marvel of 166 arches and 17 pillars in two levels. It is made of 400 large, rough-hewn granite blocks, joined without mortar or clamps. Its maximum height of 28,100 m is found at the Plaza del Azoguejo.