Atop a hill in Saint-Maurice-sur-Eygues, in the southern Côtes-du-Rhône, a structure looms at once imposing and beautiful. Constructed of rectangular earthen-yellow stones broader than a human’s wingspan, it is flanked on the entirety of its left side by an Ionic-columned portico, and punctuated on its upper level by three large circle-top windows. This is Domaine Viret, and it is only the beginning of the story of one of southern France’s most fascinating and inscrutable winegrowers.