Ribera del Duero is an important wine region in Castilla y Leon, northern Spain. Its reputation is largely thanks to the high-quality of its red wines made mainly from Tempranillo grapes. The best examples are renowned throughout the wine world.

Ribera del Duero was not awarded DO status until 1982. This is despite a long history of winemaking, centred on the leading local producer, Bodegas Vega Sicilia. Its Unico wine is generally regarded as Spain's greatest and is served at royal functions. While some wines may approach it in quality, none combine this with tradition and history to the same extent. Vega Sicilia was founded in 1864, as the pioneering estate in the area.

Tinto Pesquera is another renowned brand, created by the region's best-known winemaker, Alejandro Fernández. The success of Vega Sicilia and Pesquera quickly turned local producers away from bulk rosé and selling to co-operatives. Instead they focused their attentions on making quality reds. Other prominent producers include Dominio de Pingus and Emilio Moro.

Today, Ribera del Duero is almost entirely devoted to red wine. Tempranillo is the most widely planted grape variety, known locally either as Tinto Fino or Tinta del Pais. It produces wines which are deeply coloured, with a firm tannin structure and complex aromas of dark fruit. Most of the top examples age gracefully for years.

According to DO regulations, Tempranillo must make up a minimum of 75 percent of all vinos tintos (red wines). The balance is usually made up mostly of Cabernet Sauvignon, Merlot and Malbec. These are all varieties that were introduced by Vega Sicilia more than a century ago. Up to five percent of Albillo or Garnacha is also permitted.

Garnacha is used for most rosé wines. Albillo is the only white grape with vines planted in Ribera del Duero. It produces wines for local consumption that don't qualify for the Ribera del Duero DO title. It can also be used in tiny quantities as a softener for heavy reds.

The aging requirements used for Ribera del Duero match those of the Rioja denomination. Crianza red wines must be matured for at least two years, with 12 months in oak. Reserva wines are aged for at least three years, with one in oak. Gran Reserva wines must be aged for five years before release. two of which must be spent in oak.

Ribera del Duero is located on the elevated northern plateau of the Iberian Peninsula at 800 meters (2800ft) above sea level. Ribera del Duero means "bank of the Duero", and the river indeed divides the region. It also provides the local vineyards with a much-needed water supply. The river also provides neighbouring Portugal with it's premier wine region as it changes its name to Douro and flows through the eponymous valley, the home of Port and Portugal's best red table wines.

The region's inland location, coupled with the sheltering effects of the Sierra de la Demanda and Sierra de Guadarrama mountain ranges, creates an extreme climate. Hot and dry summers are followed by harsh winters. Temperatures can range from –18°C to 40°C (–0.4°F to 104°F) and winter. Spring frosts are a real threat here, too.

In the growing season, the high daytime temperatures are combined with considerably cooler nights. This assists in the optimum accumulation of aromas and other chemical compounds (phenolics) in the grapes. Soils here are credited with adding complexity and character to Ribera del Duero wines. Alternating layers of limestone, marl and chalk sit under silt and clay topsoil.

The capital of Ribera del Duero is the historic town of Aranda de Duero. It boasts a series of antique underground cellars (bodegas) built to store wine. The interconnecting cellars reach a depth of 40ft (12m) in places.