CLASTIDIUM (mod. CASTEGGIO), a village of the Anamares in Gallia Cispadana, on the Via Postumia, 5 m. E. of Iria (mod. Voghera) and 31m. W. of Placentia, Italy. Here in 222 B.C. M. Claudius Marcellus defeated the Gauls and won the spolia opima; in 218 Hannibal took Clastidium and its stores of corn by treachery.