The Rioja designation area, located in northern Spain in the Ebro valley, is divided into three production sectors: Rioja Alta, Rioja Baja and Rioja Alavesa. The Rioja vineyard occupies approximately 60,000 hectares spread on both sides of the Ebro over around a hundred kilometres, and is bordered by the Cantabrian Range to the north and the Sierra de la Demanda to the south. Three autonomous communities inhabit the designation area: the Rioja itself, Navarro and the Basque Country. Rioja is known for its excellent red wines (85% of production), made essentially from the tempranillo grape variety but sometimes also from Garnacha (red Grenache), Mazuelo and Graciano. Red wines, especially the most renowned, Rioja Alta, are powerful, full-bodied and well-suited to ageing. Depending on the ageing process applied, Rioja wines are classified in one of the following four categories: - ""Joven"" (young wines in their first or second year that have retained their primary characteristics of freshness and fruitiness), - ""Crianza"" (wines in their third year at least, having been kept in a barrel for at least a year and in bottles for a few months. For white wines, the minimum barrel ageing period is 6 months), - ""Reserva"" (wines selected for their strong characteristics from every vintage which have been aged in barrels for at least three years. For white wines, the minimum ageing period is 2 years, of which at least 6 months must be barrel ageing), - ""Gran Reserva"" (wines selected from exceptional vintages that have been stored in barrels for at least two years and three in bottles. For white wines, the minimum ageing period is 4 years, of which at least 6 months must be barrel ageing). The list of top producers include Compania de vinos Telmo Rodriguez, Bodegas Fernando Remirez de Ganuza, Vinos de los Herederos del Marques de Riscal, Bodegas Marques de Murrieta.