San Fabiano Castle (Italian: Castello San Fabiano) is a 13th-century castle and wine producing farm estate in Monteroni d'Arbia, Siena, Italy, built by King Charles of Anjou. The church of San Fabiano on the estate dates from the year 867 and is dedicated to Pope Fabian, one of the first Christian martyrs killed in the Coliseum. It is adjacent to two rivers, the Arbia and the Biena, and surrounded by 1,800 acres (7 km2) of vineyards, oak forests, durum wheat fields and corn fields.