The first and foremost reason why the wines of Castelli are so good is that the soil in this area, to the south-east of Rome, is volcanic and therefore rich in potassium. The climatic conditions too are extremely favorable and have led to a natural selection of the vines that were once grown on these hills. The grape varieties that eventually made it through this natural selection are Malvasia di Candia and Malvasia del Lazio, as well as several varieties of Trebbiano (white grapes) and Cesanese, Montepulciano, Sangiovese and Merlot (red grapes). It is through various combinations of these grapes that the most famous Latium D.O.C. wines are obtained. Yet, in spite of their success, these D.O.C. wines have not quite managed to fully defeat all those other wines that go by the generic name of Castelli wines and that still enjoy great popularity in the Eternal City.
Given the reality of the market, it was decided in 1996 to give these wines a D.O.C. appellation so as to promote their image while boosting their quality through strict regulations that are bearing fruit year after year.