Fortified in 1307, the town of Peñafiel was once a commercial and historic centre of the first order. Its famous castle, declared to be a National Monument in 1917, sits on a hill.

The castle's current appearance is the result of a combination of several structures, the first of them from the 9th or 10th century, and the last from the mid-15th century. It is a very well-preserved fortress, which has a length of more than 200 metres and is built in the shape of ship. The keep, more than 30 metres high, is flanked by two courtyards: one to the north, which contains the underground reservoirs and the store rooms, and one to the south, which currently houses the Provincial Wine Museum and was the site of the stables and guards' quarters. The entire town was surrounded by walls which ran down from the ends of the castle. Only four round turrets, two to the south and two to the north, and several panels remain of them. Other than the castle, the most important building in Peñafiel is the church of San Pablo, founded in 1324 by the Infante Don Juan Manuel, which is the finest example of the Valladolid region's Gothic-Mudejar architecture. Outstanding inside is the funeral chapel of the Manuel family, with elements of plateresque decoration.