Rojas Castle, Poza de la Sal

Rojas Castle (Castillo de los Rojas) in Poza de la Sal is one of the most imposing and best-preserved fortresses in the province of Burgos, rising above a small town shaped for centuries by salt extraction. The stronghold dominates the salt basin and the wider Bureba region, its silhouette visible from far away atop the rocky outcrop above the rooftops of Poza de la Sal.

What is the history behind the castle?

The site's defensive role dates back to the late 9th century, when Count Diego Rodríguez Porcelos resettled the area of Poza and built a fortification to protect newly reclaimed territory. The original castle likely stood at what is now known as El Castellar, a rise overlooking the salt amphitheater, before the stronghold moved down to its current location in the 11th or 12th century.

The wealth generated by the nearby salt works turned Poza into a strategically important place, prompting the construction of a strong fortress and the walling of the entire settlement. Ownership of the castle shifted several times over the centuries — in 1035, under the will of Sancho the Great, it even passed briefly under the crown of Navarre. A turning point came in 1298, when King Ferdinand IV granted the original fortress and the town to Juan Fernández de Rojas in reward for services to the crown.

It was the Rojas family who, in the 14th century, built the castle that stands today, raising it over the foundations of the earlier structure. The family took full control of the surrounding salt operations, securing for themselves both a residence and effective defense of the settlement.

The castle also witnessed events of international significance: between 22 January and 19 May 1528, ambassadors from France, Milan, Florence, England and Venice were held here on the orders of Emperor Charles I. Later, Napoleonic troops made use of the fortress during the French occupation, and it served as a watchtower during the Carlist Wars.

What can you see at the site today?

Rojas Castle impresses with its solid stone structure and strategic position, from which defenders once watched over the salt pans, the entrance to the town, and the whole Bureba basin. Today the castle hill offers one of the best panoramas over Poza de la Sal, including a clear view of the striking salt diapir — a crater-like geological formation designated a National Site of Geological Interest and considered one of the finest examples of its kind in the world.

At the foot of the castle, it is worth walking down into the town's medieval core, declared a Historic-Artistic Site in 1982, with its maze of narrow, winding streets. Nearby stands the parish church, listed as a National Monument for its Gothic interior, along with the Salt Interpretation Centre, housed in the former 18th-century administration building of the Royal Salt Works, where visitors can learn about the traditional salt extraction process. The town also hosts a space dedicated to naturalist Félix Rodríguez de la Fuente, who was born in Poza de la Sal.

How to get there and when to visit?

Poza de la Sal lies about 43 kilometers from Burgos, in the Bureba district, and is easily reached by car via local regional roads. The castle sits on a hill above the town, so reaching it involves a short uphill walk — comfortable footwear is recommended. Spring and autumn are the best seasons to visit, offering mild temperatures and the clearest views from the walls; summer midday heat can be intense on the exposed hilltop.

Frequently asked questions

Who built the castle in Poza de la Sal? The current structure was built in the 14th century by the Rojas family, on the foundations of an earlier 9th- to 11th-century fortification raised by Count Diego Rodríguez Porcelos.

Why is the castle called "de los Rojas"? The name comes from the Fernández de Rojas family, who received the fortress and the town from King Ferdinand IV in 1298 and went on to control the surrounding salt works.

What else is worth seeing besides the castle? Highlights include the medieval town center, the Gothic parish church, the Salt Interpretation Centre, and the salt diapir recognized for its exceptional geological significance.

Is the walk up to the castle difficult? No — the castle sits just above the town, and reaching it only requires a short, occasionally steep walk on foot.