Covering an area of 5,400 hectares and with a viticultural history dating back many centuries, the vineyards of the appellation account for just over one twentieth of the entire [Bordeaux](/region/bordeaux) region and include the eight communes of Saint-Christophe-des-Bardes, Saint-Hippolyte, Saint-Étienne-de-Lisse, Saint-Laurent-des-Combes, Saint-Pey-d’Armens, Saint-Sulpice-de-Faleyrens, Vignonet and Saint-Émilion itself. Four other red wine AOCs to the north / northeast of the appellation - [Lussac-Saint-Émilion](/appellation/lussac-saint-emilion-aoc), [Montagne-Saint-Émilion](/appellation/montagne-saint-emilion-aoc), Puisseguin-Saint-Émilion and [Saint-Georges-Saint-Émilion](/appellation/saint-georges-saint-emilion-aoc) - are collectively known as the Saint-Émilion satellites, and produce stylish, affordable blends in the traditional [Bordeaux](/region/bordeaux) style. Saint-Émilion itself benefits from a temperate climate with extremes of summer heat and winter frosts moderated by the close proximity of the Dordogne river. Soil diversity is a key feature of the appellation’s terroir with the central limestone plateau characterised by chalky, clay soils and the north and northwest of the appellation having a more sandy, gravelly composition. Wines from Saint-Émilion are typically a blend of two or more varieties, the most common components of which are [Merlot](/merlot) (accounting for approximately 60% of the appellation’s vineyards), [Cabernet Franc](/cabernet-franc) (almost 30%) and [Cabernet Sauvignon](/cabernet-sauvignon) (roughly 10%). Other permitted grape varieties are [Malbec](/malbec), [Petit-Verdot](/petit-verdot) and [Carménère](/carmenere) although these are grown in minuscule quantities by comparison with the three leads. The first vineyard area to be recognised as a UNESCO world heritage site (1999), Saint-Émilion has classified its wines into four categories since 1955. The most recent classification took place in 2012 with four of the appellation’s estates - [Château Angélus](/producer/chateau-angelus), [Château Ausone](/producer/chateau-ausone), [Château Cheval Blanc](/producer/chateau-cheval-blanc) and [Château Pavie](/producer/chateau-pavie) - awarded the highest level ‘Premier Grand Cru Classé A’ considered the equivalent of the First Growths in the Médoc. In order to be labelled as such, estates are assessed on their wines (twenty vintages must be provided), their terroir, and their reputation, including the value of their past vintages in the secondary market place. Other classifications are ‘Premier Grand Cru Classé B’ (fifteen estates), ‘Saint-Émilion Grand Cru Classé’ and ‘Grand Cru’. The dominance of [Merlot](/merlot) in most Saint-Émilion blends delivers an elegant, seductive wine with a bright ruby-red colour and red fruit aromas. The Cabernet varieties add tannic structure and ageing potential resulting in wines that can be consumed young, but which will undoubtedly benefit from a period of ageing in the bottle, evolving into silky smooth, decadent wines of great complexity.