JACA, a city of northern Spain, in the province of Huesca, 114 m. N. by W. of Saragossa, on the left bank of the river Aragon, and among the southern slopes of the Pyrenees, 2,38o ft. above the sea. Pop. (1930), 7,056. The origin of the city is unknown. The Jaccetani (Tuaarravol) are mentioned as one of the most celebrated of the numerous small tribes inhabiting the basin of the Ebro by Strabo. They are probably identical with the Lacetani of Livy (xxi. 6o, 61) and Caesar (B.C. i. 6o). Early in the 8th century Jaca fell into the possession of the Moors, by whose writers it is referred to under the name of Dyaka as one of the chief places in the province of Sarkosta (Saragossa). It
was reconquered bef ore the time of Ramiro I. of Aragon (1035– 1063), who gave it the title of "city," and in 1063 held a council within its walls. During the Peninsular War Jaca surrendered to the French in 1809, and was recaptured in 1814. Jaca is an episco pal see, and was formerly the capital of the Aragonese county of Sobrarbe. Its massive Gothic cathedral dates at least from the 11th century, and possibly from the 9th.