The chalk walls ensure constant temperature (about 48 °F) and humidity for aging wine. At the beginning of the 20th century the house commissioned artist André Navlet to design reliefs on the cellar walls. The Veuve Clicquot chalk quarries are located beneath the colline Saint Nicaise and are granted UNESCO World Heritage Site status. Vineyards The first vineyards were owned by Philippe Clicquot near Verzy and Vernezay. The second group of vineyards was the "Bouzy holding" inherited by François Clicquot from his grandmother Muiron in 1804. These two vineyards were enlarged by purchases made by Madame Clicquot. She thus became proprietor of of high-quality vines around Bouzy, Vernezay and Verzy. When establishing her own vineyards, she bought only vines on land that would subsequently be classified 100% on the "échelle des crus" (Bouzy, Verzenay and Verzy). When asked about the quality of her wines, she answered: "we have only one quality, the finest". This remains the company's motto. When Madame Clicquot took the reins of the company, she spent as much time as possible in the vineyards. Although she was head of the company, she was devoted to the craft of wine making. Between 1872 and 1873, Alfred Werlé acquired at Le Mesnil and enlarged the Bouzy vineyards by . In a single year, he doubled the vineyard holdings that the company had amassed over a century. Alfred stepped up his acquisition program in 1884, buying a total of . He also bought Duchesse d'Uzès's vineyards to return the vines she had inherited from Madame Clicquot into the company's ownership. The policy of extending the Veuve Clicquot vineyards was pursued by Bertrand de Mum. The last acquisitions were 61 acres at Saint-Thierry, purchased between 1967 and 1975. The house now owns of vineyards, with an average rating of 71% on the "échelle des crus". Fifty-five percent of Veuve Clicquot's vineyards are categorized as Grand Cru and 40% are Premier Cru. The vineyard is planted with 50% Chardonnay, 45% Pinot Noir and 5% Meunier. The company also purchases grapes from 400 different suppliers, some of whom are descendants of the wine growers who sold their harvests to Edouard Werlé. Innovation The natural sparkle is created by the sugar and yeast present in the grape. The interaction between these two elements creates carbon dioxide with varying quantities of bubbles. In the 19th century, neither sugar nor yeast was added to the finished