Toward the end of the 1st century BC, the Celtiberian town of Salduba at the site was taken by the Romans, who made it a colony under Emperor Augustus with the name of Caesaraugusta (from which its Arabic name Saraqustah and its present name were derived). The chief commercial and military station in the Ebro valley, it was one of the first towns in Spain to be Christianized, and it had a bishop by the middle of the 3rd century AD. In 380 a church synod at Zaragoza condemned the Priscillianist heresy of absolute renunciation of all sense pleasures. After falling to the Germanic Suebi and then to the Visigoths in the 5th century, the town was taken by the Moors c. 714. In 778 it was besieged by the Frankish king Charlemagne, who had to withdraw because of a Saxon rebellion in his domain. After being captured by the Almoravids in 1110, Zaragoza was taken by King Alfonso I of Aragon in 1118 and thereafter enjoyed three and a half centuries of prosperity as capital of Aragon. In the Peninsular War it was famed for the heroic resistance of its citizens under Gen. José de Palafox y Melzi during a protracted siege (1808-09) by the French, who finally took the city. Among the defenders was María Agustín, the "Maid of Saragossa," whose exploits are described in Lord Byron's poem Childe Harold.

The seat of an archbishop, Zaragoza has two cathedrals, the older of which is the Catedral de La Seo (Latin sedes), or Catedral del Salvador, chiefly a Gothic building (1119-1520) but showing some traces of the earlier Romanesque church built on the site of the first mosque erected in Spain. The Catedral Nuestra Señora del Pilar, dedicated to the Virgin of the Pillar who is patron of all Spain, commemorates the traditional appearance on Jan. 2, AD 40, of the Virgin Mary standing on a pillar erected in honour of Saint James the Great, whose shrine is at Santiago de Compostela. The cathedral was begun in 1681 to a design by Francisco Herrera the Younger (El Mozo) and contains some frescos by Goya. The 14th-century Gothic churches of San Pablo and the Magdalena and the Renaissance church of Santa Engracia are also notable. Outstanding secular buildings include La Lonja, or The Exchange, in Plateresque Gothic style; the Palace of the Counts of Luna (1537), in which the Court of Justice sits; and the 17th-century Palace of the Condes de Sástago y Argillo. The Aljafería Palace, to the west of the city, contains an oratory dome and tower that are among Spain's best examples of Islamic civil architecture. The University of Zaragoza was founded in 1474, the medical school being its most famous faculty, but the buildings date from later periods.