The castle of Ponferrada, also known as the Castle of the Templars, is a medieval fortress located in Ponferrada, in the region of El Bierzo. It is located on a hill at the confluence of the rivers Boeza and Sil. Its construction dates mainly from the twelfth to fifteenth centuries, with several extensions and modifications over time.

Initially built by the Order of the Temple in the 12th century, the castle played a fundamental role in the defense and control of the northwestern region of Spain. After the dissolution of the order in the 14th century, the fortress became the property of the Catholic Monarchs and then of various nobles, which led to further extensions and improvements. This castle is an outstanding example of medieval military architecture, with an area of more than 8,000 square meters that includes robust walls, defensive towers and a complex system of courtyards and internal outbuildings.

Today, the castle of Ponferrada is one of the main tourist attractions of El Bierzo, as well as being a key point on the Pilgrim's Route to Santiago de Compostela. It has been declared an Asset of Cultural Interest.

The castle is located on a site that was probably a Celtic castro, like others in the region of El Bierzo. It is also believed to have been used as a Roman and later Visigoth settlement.

In 1178, King Ferdinand II of León allowed the Knights Templar to establish a commandery in Ponferrada. In 1180, the monarch granted a charter for the repopulation of the town, and the first fortification was built in 1187. In 1196, Alfonso IX of León took Ponferrada from the Templars due to their alliance with Castile. However, in 1211, after making peace, Alfonso IX returned the town to the Templars in exchange for some castles. During the reign of Ferdinand IV, the order was dissolved after a trial in France, and the master of the Temple in León gave Ponferrada to the prince Don Felipe.

In 1340, Alfonso XI gave Ponferrada to Pedro Fernández de Castro, his chief steward, who probably began the construction of the old castle. In 1440, Pedro Álvarez Osorio, first Count of Lemos, took control of Ponferrada and carried out important works that shaped the current fortress. During the Irmandiña Revolt of 1467, Galician peasants attacked the castle, but thanks to an agreement between Henry IV and the Count of Trastámara, the fortress was saved.

After family disputes over the ownership of Ponferrada, the Catholic Monarchs awarded the town to Juana Osorio. Her rival, Rodrigo Osorio, did not accept the decision and rebelled against the Crown, which led to a siege in 1486 by royal troops. After the fortress was taken, reinforcement and repairs were carried out under the administration of Juan de Torres de Navarra, cousin of the monarchs.

In the 17th and 18th centuries, the castle was administered by a corregidor on behalf of the Crown, but its military importance gradually declined, leading to its abandonment.

During the Spanish War of Independence, the castle was briefly used by French troops as a strategic point, but it was in a deteriorated condition. After the withdrawal of the French troops, the castle again fell into disuse.

From 1850 onwards, the castle suffered accelerated deterioration due to the sale of its stones for the construction of local infrastructure. It was not until 1924 that it was declared a National Monument, slowing its deterioration.

Today, the castle hosts the Templar Nights, a cultural event that revives the era of the Knights Templar with parades, medieval music, and craft markets. One of the highlights is the investiture ceremony for new Knights Templar.

The castle has an irregular polygon shape and is divided into two parts: a northern part from the 12th century and the rest of the castle built mainly in the 15th century. It was originally surrounded by a moat, except in the northwestern part where the river served that function. Inside the castle are 12th century Templar fortifications, including the remains of a barbican, several towers and a cistern.

The northwest façade ends in the Moclín tower, while the main masonry doorway has two towers flanking a semicircular arch. There are also perimeter remains of circular constructions that could be pre-Roman. During the 19th century, the castle suffered significant damage due to the use of its stone for local constructions, but it has been partially restored and preserved as a historical and tourist monument.