Loire Valley (wine) a variety of limestone with excellent drainage that is known as tuffeau which is the same material used to build many of the famous Loire Valley Châteaux. The area around Chinon, Bourgueil and Saint-Nicolas-de-Bourgueil produces the majority of the Loire Valley's red wine based on the Cabernet franc grape—known in this areas as "Breton". The wines of the Chinon area are the softest and rich expression of the grape while the Bourgueil area produces more tannic and firm wines. The St-Nicolas-de-Bourgueil area produces the lightest colored wines. In the 19th century, the wines of the Chinon area were compared favorably
Loire of the estuary), and the beaches of Le Croisic and La Baule along the coastline. Its main tributaries include the rivers Maine, Nièvre and the Erdre on its right bank, and the rivers Allier, Cher, Indre, Vienne, and the Sèvre Nantaise on the left bank. The largest tributary of the river is the Allier, in length, which joins the Loire near the town of Nevers at . Downstream of Nevers lies the Loire Valley, a UNESCO World Heritage Site due to its fine assortment of castles. The second longest tributary is the Vienne which joins the Loire at Candes-Saint-Martin at