Alcaudete Castle has its origins in a small settlement located on the summit of the hill the fortress stands on today. The complex was comprised of simple structures, including palisades and walls of masonry and rammed earth to reinforce the main access points. These elements have since disappeared, although their materials may have been reused to build the defensive structure erected during the Almohad period, which lasted from the 12th to the 13th century. 

During this period, the town centre was moved partway down the slope and encircled by a stockade, while an alcázar with a polygonal layout and stepped or terraced base was built on the summit of the hill. The walls were reinforced with robust, square-shaped towers positioned along the straight sections, acting as masonry buttresses, while turrets accessed from the rear were placed on the corners of the walls to serve as bastions. The walls themselves had masonry foundations upon which stood ramparts of rammed earth. Within the enclosure, a number of structures including rammed-earth walls and a rectangular cistern have been found.

Midway through the 13th century, the Order of Calatrava made a series of major modifications, including adding masonry cladding to the old walls that surrounded the town and increasing the number of defensive towers. They converted the enclosure surrounding the old alcázar into an outer wall, making it significantly lower, and built a new fortress inside the site, leaving a narrow passageway or outer bailey between the two structures.
The new fortress had a polygonal layout and was constructed from irregular masonry and lime mortar. It was crowned by six towers, accessed via the parapets that ran along the walls and enabled soldiers to walk the entire perimeter of the enclosure. The castle had two gateways: the main entrance at the north end, which was defended by two square-shaped towers with rounded corners; and a small postern gate at the south-east end, defended by what is known as the Torre del Reloj, the “Clock Tower”. 

The main entrance led to a moat and walkway formed by the castle walls and the rocky escarpments inside the site, beyond which lay a raised central terrace or platform which the most important parts of the castle stood on. At a lower level there were two cisterns, one beneath the gatehouse and the other next to the entrance to the stables.

The bailey, located at the far north-west end of the site, was an open space in front of the gatehouse, a rectangular building constructed from irregular masonry and directly connected to the parapet on the north-west wall. The cloister, located in the south of the complex, comprised a small courtyard near the keep and chapter house. Only a few of its architectural elements (including a column and capital) have survived. Next to the cloister there were two buildings, one housing a kitchen, storage rooms and sleeping quarters, and the other containing the stables (on the lower floor) and a large chapter house (on the upper floor) accessed directly via the cloister. The eastern part of the raised terrace (opposite the keep) was home to the chapel, next to which were the kitchens and sleeping quarters for the garrison. 

The keep was located at the highest and most central point of the raised terrace, conical in shape with a rectangular base and had masonry walls some 3 m thick. The keep’s interior was accessed by a staircase attached to the north-east corner. Upon reaching the first floor, visitors to the keep then had to cross a projecting balcony or scaffold via a retractable wooden platform. The keep had three storeys: the first housed the storeroom and cistern, and was reached via a hatch set into the floor above; the second served as a transit area; and the third housed the residence of the castle’s commander.

During the Renaissance era, the castle lost its military function and was converted into a residential palace. Within the site, new residential and palatial structures were built around the keep; these comprised a complex network of elegant rooms, porticoed courtyards and hallways, which were reached after passing through the Puerta de la Reja gateway and the main entrance to the palace area. Adjoining the nobility’s quarters were the service areas including storerooms, kitchens and stables, which occupied the north-west end, the area around the gatehouse and the palace entrance. In order to carry out these renovations it was necessary to demolish earlier structures such as the chapel, the staircase access to the keep, and the postern gate, and reduce the size of others such as the bailey and the moat and walkway. Additionally, areas such as the stables and the chapter house were subdivided and repurposed.

Alcaudete is identified with the Flavian settlement of Sosontigi, a name written on an honorific inscription found in the area. Although no Roman remains have been discovered within the town itself, numerous discoveries have been made nearby, chiefly in the areas around the park, secondary school and industrial estate.

Between the 8th and 10th centuries, following the Muslim conquest, a small settlement named Hisn al-Qabdaq was established on the summit of the hill now crowned by the castle. The hill was the ideal location for a defensive fortification, owing to the natural defences provided by its rugged terrain. After the Almohad conquest, the settlement was moved partway down the slope and encircled by a protective wall, while an alcázar was erected on top of the existing defensive structures on the summit.

The area was subsequently conquered by Christian forces, and owing to its highly strategic location on the border with the Nasrid kingdom of Granada, in 1246 King Ferdinand III of Castile made Alcaudete a feudal estate of the Order of Calatrava, which proceeded to substantially strengthen its defences.

Despite these improvements, in 1300 Alcaudete was temporarily recaptured by Muslim forces, who held it until 1312 when the estate was taken back by Prince Peter and placed under royal jurisdiction by Alfonso XI. In 1385, King John I of Castile granted it as an entailed estate to Alfonso Fernández de Montemayor, Governor of the Border. Alcaudete remained part of the Montemayor estate until the 16th century, having been awarded the status of county during the reign of Emperor Charles V.

During the 17th century, now in the hands of the Fernández de Córdoba family, the fortress-turned-palace fell into disrepair and was eventually abandoned. By the 18th century, the castle had become a ruin. Since the late 20th century, it has been the focus of a long-term archaeological study and restoration process.