Vega Sicilia is widely regarded as the greatest wine producer in Spain. The estate in Ribera del Duero is known for its dense, complex red wines made principally from the Tinto Fino (Tempranillo) grape variety. Its top wine, Unico, is one of Spain's most expensive and sought-after wines.

The Vega Sicilia estate covers around 1000 hectares (2470 acres) of which around 210ha (520 acres) is under vine. It has been in operation since 1864, long before the development of the appellation in which it resides, and the current wine styles date from the 1910s. Quality has become more consistent since the current owners, the Alvarez family, took over in 1982.

The vineyards are planted to around 80 percent Tempranillo with the remainder taken up by Cabernet Sauvignon, Merlot and tiny amounts of Malbec. Yields are kept low, aided by green harvesting and painstaking grape selection. Winery operations are just as meticulous, with a complicated series of rackings from large barrels to barriques, mixing old and new oak and leading to wines that are capable of long aging.

Vega Sicilia makes three cuvées: Unico is the flagship, and the Reserva Especial is a blend of several of the best vintages. Traditionally they would be aged for 10 years or more before release, although this has been reduced in recent vintages. The junior wine, Valbuena, is made from younger vines, and is released after five years in American oak.

Vega Sicilia also owns the nearby Bodegas Alion, which produces high-quality varietal Tempranillo wines for earlier consumption, as well as Bodegas Pintia in Toro and the Tokaj estate Oremus. In addition, Macán is a Rioja estate created in 2009 as a joint-venture with the Compagnie Viticole Baron Edmond de Rothschild. It lies to the northeast of Samaniego and features a gravity-fed winery built over four levels.