Led by prominent wine critic Luigi Veronelli, there was a push to have the vineyards of Barolo classified according to the quality of their produce. Winemaker Renato Ratti conducted an extensive study of the soils, geography and produce of vineyards throughout the area and mapped out individual plots based on their quality potential. The "Ratti Map" is still widely used by producers and negociants today. While there is no official designation of cru vineyard in the Barolo zone, both oral tradition and the history of high prices paid by negociants has elevated some vineyards to "cru" status in Barolo. In the commune of Barolo the "Cannubi" and "Sarmassa" are considered "cru" class as well as the "Brunate" vineyard shared with the commune of La Morra. Also in La Morra is the highly esteemed "Cerequio" and "Rocche" vineyards. In Castiglione Falletto is the "Monprivato" and "Villero" vineyards. The commune of Serralunga d'Alba is home to the esteemed vineyards of "Lazzarito" and "Vigna Rionda" while the commune of Monforte d'Alba is home to the "Bussia, Ginestra" and "Santo Stefano di Perno" vineyards.