Castillo de Foncastín stands in Rueda, Valladolid, as a 15th-century fortress built by Álvaro de Lugo around 1465. Originally designed with a large rectangular enclosure, three corner towers, and a keep, the castle served dual purposes: collecting tariffs and maintaining reserve troops along an important medieval trade route known as the cañada real. The castle followed the architectural style characteristic of the Valladolid school. Though substantial remains are limited today, the surviving cylindrical brick tower with attached wall fragments testifies to centuries of regional history and the strategic importance of this location in Castile and León.
