Calahorra (käläôr`rä), town (1990 pop. 18,869), La Rioja prov., NE Spain, on the Cidacos River near its confluence with the Ebro. Calahorra is a farming (cereals and grapes) and manufacturing center. Known in ancient times as Calagurris, it is the place where Pompey unsuccessfully besieged (76–72 B.C.) the rebel Sertorius. An old cathedral (c.5th cent.; restored 15th cent.) and some Roman ruins survive today, and the Casa Santa, where the martyrs Emeterius and Celedonius are said to be buried, is the site of an annual pilgrimage. Quintilian was born in the town.