A viaduct is a bridge composed of several small spans for crossing a valley or a gorge. The term viaduct is derived from the Latin via for road and ducere, to lead. The ancient Romans did not use the term; it is a modern derivation from an analogy with aqueduct. Like the Roman aqueducts, many early viaducts comprised a series of arches of roughly equal length. Viaducts may span land or water or both.