The legacy of Sassicaia begins in 1944, when Mario Incisa acquired a number of Cabernet Sauvignon and Franc vine cuttings and planted them on a sloping hillside of the San Guido estate, called Castiglioncello after the 11th-century castle at the vineyard's upper edge. This tiny, 3.75-acre vineyard stood alone until 1965, when a second Cabernet vineyard was planted with cuttings from the Castiglioncello parcel; the gravelly, 30-acre plot would give the wine its name: Sassicaia, "the place of many...