 The exclave arose when the Province of Lodi was carved out of the Province of Milan, but a referendum in San Colombano indicated the locals' wish to stay in Milan.As a result, the comune is the only wine–producing area in the mostly urbanized Metropolitan City of Milan.The commune of San Colombano al Lambro is home to the "Denominazione di origine controllata" (DOC) wine which includes 100 hectares (250 acres) producing a single red wine.