Designed like a great ship sailing the plateau, Peñafiel castle is a perfect example of the so-called castillos roqueros - the rock castles or mountain castles, firmly fused with the outcrops that support them. Count Sancho Garcia baptised this "the most faithful rock in Castile" in the eleventh century, after a strong record of defending against the Moors. Offering a clear vantage point over seven valleys, at the confluence of the rivers Duero and Duraton, its current appearance is the result of successive reforms by the Infante don Juan Manuel between the thirteenth and fourteenth centuries in ogival-Germanic style, and by don Pedro Giron, Master of the Order of Calatrava, in the fifteenth century, who was responsible for the 34 metre-high keep.

In addition to the Infante don Juan Manuel - as famous for his power and his independence from the monarchy as for his literary works (some of them, such as the Libro del Conde Lucanor, true classics of Spanish literature) - the castle had other illustrious residents. These include the unfortunate prince of Viana, the son of Juan II and Blanca de Navarra, who was born within its walls, and whose death by poisoning, brought to an end a long history of clashes between the crowns of Aragon and Navarre. Today, the castle of Peñafiel is known as much as for its status as the Provincial Museum of Wine, as for its history. The old apartments of the fortress have been transformed into exhibition rooms, tasting rooms, wine cellars and oenology centre dedicated to the extraordinary wines of Ribera del Duero, with nearly one hundred thousand visitors annually.