Why did the famous French architect Eugene Viollet-le-Duc only work on one residence: the historic Roquetaillade Castle? Why is there a monolithic church in Saint-Emilion? And why did its monk sleep underground? Why is there a giant wall around the tiny village of Blaye? And why was beautiful Bourg-en-Gironde built into the side of a cliff? And how do Cadillac and Pauillac make time stand still?