Sos stands on a hill which centuries ago was a vantage point overlooking neighbouring Navarra, involved in civil war throughout the 15th century. It became famous as the birthplace of Ferdinand the Catholic, the last king of Aragon before its union with the Kingdom of Castile. This birth was the result of political machinations worthy of a soap opera: his father, Juan II of Aragon, disputed the throne of Navarra with his son Carlos, Prince of Viana, the child of his first marriage to Blanca of Navarra. Because of this, the mother of the future Catholic Monarch, Juana Enríquez, preferred to have her son in a safe place, in Aragon, and chose Sos, home of the noble Sada family, who were loyal to the king. 

A walk through history. 

The wall and the seven entrances to the town survive intact. Before we go in to discover the heritage of Sos, it is worth pausing to admire the view of the beautiful site from the road. In the town, our walk can begin at the Puerta de Zaragoza, the gate where the main street, Calle Fernando el Católico, begins. We should stroll slowly enough to enjoy the mansions and their Gothic and Renaissance details. Along the way we find the Palacio Español de Niño, soon to become a conference centre. Next to it is the Palacio de Sada, where the king was born and which now holds an interpretation centre devoted to Ferdinand the Catholic. This centre organises guided tours of the town and is open from Wednesdays to Fridays from 10 am to 2 pm, and 4 pm to 7 pm, and is open every day in summer. Tours must be booked in advance. Before we reach the castle crowning the town, we come to the medieval market hall. Part of its floor is from the former prison of Sos, and we can see inscriptions made on it by prisoners during the Civil War and the post-war period. 

The remains of the fortress. 

Finally we come to the castle and the church of San Esteban. They stand on one of the two promontories of the town, Peña Feliciana. Only the exterior and the keep remain of the ruined castle. In the church of San Esteban, the main church of the town, is the font where Ferdinand the Catholic was baptised. Inside, we can also visit the museum of religious art, which holds artistic treasures such as Baroque canvases, Gothic carvings and numerous metalwork pieces. Outside the walled town we find the monastery of Valentuñana, built after an apparition of the Virgin, commemorated by a 13th century wood carving. 

Music on the battlements. 

Once a year Sos combines its spectacular heritage with good music. The Luna Lunera festival is held every summer in the exceptional setting of the Plaza de la Lonja. The festival attracts well-known musicians from Spain and abroad. Earlier editions have seen performances by Paco de Lucía, Eli “Paperboy” Reed, Elvis Costello and Jorge Drexler, among others. 

Where to eat. 

On Calle de Fernando el Católico we find the restaurant La cocina del Principal. In a 15th century house and with a welcoming atmosphere, it serves the traditional dishes of the area, such as ternasco (lamb), accompanied by jazz. Another option, given the proximity of Navarra, is to visit the village of Javier, about 14 kilometres away, and its Hotel Xabier. Its cooking is based on seasonal produce, treated with care.