 The medieval name "castri de Casule" was first recorded in 878 AD in the "Memoriatorium abbatis Berthari", a manuscript conserved in the Abbey of Monte Cassino.The village was controlled, in the fourteenth century by the Orsini family, who fortified the Norman castle.Casoli became famous as part cultirale in the nineteenth century, when the Mayor Pasquale Masciantonio housed in the castle the poet Gabriele d'Annunzio.