Las Navas de Tolosa Castle comprises a trapezoid-shaped walled enclosure with a hexagonal tower in its north-east corner. It may also have had a second, outer enclosure, as suggested by the sections of wall that can still be seen in the area around the castle.

The castle walls, now in ruins, may have been constructed from rammed earth and mortar on a masonry base, adapting to the rocky plateau on which the castle sits, which serves as both the foundations and part of its defences. Inside the enclosure there are several sections of wall that may have formed part of internal rooms and perhaps even a cistern. 

Two entrances to the fortress’ interior still remain. The main entrance was located on the west side, and protected by a bent wall abutting an escarpment of bare rock. On the east side of the site, next to the tower, there is a narrow postern gate partially hidden by a rocky outcrop that shields the gate from view while creating a winding passageway leading up to it.

The tower, constructed from rammed earth which is very dense owing to its high level of lime content, reaches a height of 14 metres on its outer side but only 2 metres on the inner side. On the tower’s plastered exterior we can still make out a number of lines that formed part of a decoration resembling ashlars or stonework (a technique known as falso despiece), especially in the area around the postern gate. 

The tower’s interior consists of a large rectangular space, encircled by a narrow passageway. This space may have been used as a cistern that collected and stored rainwater, and would have been covered by a ceiling that held up the tower’s upper floor. 

To the north-east of the fortress there are traces of a rectangular building with internal dividing walls, which may be the remains of a shrine erected shortly after the Christian conquest. The other walls we can see nearby could point to the existence of a small hamlet. 

The Despeñaperros region has drawn settlers since prehistoric times, owing to its rugged terrain housing numerous caves and rocky overhangs, and its natural beauty that makes it the ideal location for holy sites. 

However, it was the region’s strategic value in relation to the natural passes through the Sierra Morena mountains that resulted in the construction of fortifications during the Middle Ages (and even earlier), in order to control the routes of communication between the meseta region and al-Andalus. 

Although this small plateau may have been inhabited as far back as the Bronze Age and the Roman era, Las Navas de Tolosa Castle was built between the 11th and 12th centuries by the Muslims in order to control the natural passes of Despeñaperros. Years later, they bolstered its defensive role in an attempt to stop the advance of the Christian troops. Along with Castro Ferral, the castle became one of the gateways controlling the pass of Puerto del Muradal, which made it a target. After the Battle of Las Navas de Tolosa, it passed definitively into Castilian control. 

The castle played a key role in this battle, which was fought on 16 July 1212 and was one of the most significant events in the medieval history of the Iberian Peninsula, owing to its impact on the advance of the Christian kingdoms into al-Andalus. Conceived as a crusade, it was a conflict in which the routes and passes into the meseta region became of critical importance. The battle pitted a coalition of Christian kings, namely Alfonso VIII of Castile, Peter II of Aragon and Sancho VII of Navarre (who were supported by Pope Innocent III), against the Almohad Caliph Muhammad al-Nasir, whose army included contingents from the Maghreb region, sub-Saharan Africa and Turkey.

On 12 July 1212, troops led by Diego López de Haro seized control of the Puerto del Muradal. Two days later, after having their progress blocked at the pass of La Losa, the Christians camped at the site known as Mesa del Rey. From there, they engaged the Almohad army in battle and emerged victorious.

Following the victory of the Christian forces, Las Navas de Tolosa Castle remained an important fortification on the Muradal route throughout the 13th century, as it was one of the strategic outposts that guarded the passage of troops during the conquest of the Upper Guadalquivir region. In 1217, the Archbishop of Toledo seized control of all of the castles in the region, with the blessing of Pope Honorius III, who decreed that they marked the boundary of the archdiocese of Toledo. 

According to documentary records, this area was repopulated by Castilian settlers over the course of the 13th century, and the castle was demolished in 1473 on the orders of the city of Baeza.