The origins of the town of Frías date back to the 9th century. It later experienced significant growth when, in the 12th century, Alfonso VIII repopulated the valley to reinforce the border between Castile and Navarre. The town centre preserves its medieval layout and atmosphere.
The Castle of the Dukes of Frías stands on the highest rocky summit of a hill. It still has beautiful mullioned windows and Romanesque capitals from the 13th century and offers a breathtaking panoramic view. In the town centre, highlights include the Church of San Vicente, whose Romanesque façade was transported to New York after the tower collapsed in 1904, and the Convent of Santa María de Vadillo, founded at the beginning of the 13th century. Near the village, over the Ebro River, stands a beautiful medieval bridge with a 14th-century guard tower.