Aqua Claudia, ("the Claudian water") was an ancient Roman aqueduct that, like the Anio Novus, was begun by Emperor Caligula (12–41 AD) in 38 AD and finished by Emperor Claudius (10 BC – 54 AD) in 52 AD.Together with Aqua Anio Vetus, Aqua Anio Novus, and Aqua Marcia, it is regarded as one of the "four great aqueducts of Rome".