Cantar de Mio Cid, (English: “Song of My Cid”, ) also called Poema De Mio Cid, Spanish epic poem of the mid-12th century, the earliest surviving monument of Spanish literature and generally considered one of the great medieval epics and one of the masterpieces of Spanish literature. The poem tells of the fall from royal favour and the eventual vindication of the Castilian 11th-century noble and military leader Rodrigo Díaz de Vivar (1043–99), popularly known as the Cid, who became Spain’s national hero. The original manuscript of the poem, believed to have been composed about 1140, has been lost; the