The defenses built around the town of Alarcón in Cuenca include the castle of Alarcón. This fortress consists of five carefully placed isolated outlying towers, as well as a walled enclosure that houses the town center and the castle itself. Since 1992, it has been designated a Site of Cultural Importance.

The fortress, which of Arab in origin, was first reliant on the Córdoba emirate. It was submissive to Toledo's rule following the dissolution of the Caliphate of Cordoba and the creation of the Taifa kingdoms. While it was still under Muslim hands, it acted as a protective stronghold throughout their internal conflicts. Alfonso VIII's chief of the army, Fernán Martnez de Ceballos, besieged the citadel for nine months in 1184 before taking it for his monarch on Saint Andrew's Day. He was granted the right to adopt the town's name as his last name, which he did, becoming Martnez de Alarcón and establishing this new lineage.

From that point forward, the castle of Alarcón merited the attention of the succeeding kings of Castile, who rebuilt and expanded it while also giving it its own charter (1186) and the lordship of vast surrounding lands. According to Father Burriel, the alfoz was made up of 63 settlements, including Belmonte, Castillo de Garcimuoz, Albacete, La Roda, and Villarobledo. On October 18, 1194, Alfonso VIII officially donated this castle, half of the portages of Alarcón and Alconchel, the village of Las Gascas, Villamelendro, Villasila, and other property to the Military Order of Santiago in Alarcos. The Order received a second gift from Alfonso VIII a month later, on November 24, in Toledo, where he also gave it in exchange for the castle of Alarcón, a fifth of the village's rents, the hamlet of Las Gascas, and half of the portages of Alarcón and Valera de Roa, the villages of Villasila and Villamelendro. The council of Alarcón participated in the crucial battle of Las Navas de Tolosa in 1212 by providing its own forces in addition to the king's.

Fernando IV granted the Infante Don Juan Manuel the lordship of Alarcón, which included the fortress, conditionally in 1297 and formally on March 23, 1305, at the beginning of the 14th century. He wrote several of his literary works at this honorable hideaway. Once the prince passed away, his son Fernando Manuel de Villena and then his granddaughter Blanca took possession of it. Pedro I later found it and gave it back to the royal estate. Alfonso of Aragon the Older received it from Henry II and was created Marquis of Villena in 1372, but Henry III removed him in 1395, returning it to the Crown. Ultimately, Don Juan Pacheco, Marquis of Villena, received it in the 15th century. In an argument with the Catholic Monarchs, the marquisate—represented by Don Juan and his son Don Diego López Pacheco—sided with Juana la Beltraneja. They prevailed in this conflict and were able to hold onto the strongholds of Belmonte, Garcimuoz, Alarcón, and the Duchy of Escalona.

The castle of Alarcón experienced the deterioration typical of an unoccupied and abandoned structure after the Middle Ages. In 1712 it belonged to the Marquis of Aguilar and the master builders wrote up a report in which they declared that it was required to rapidly rebuild it to avoid it from collapsing.

The stone blocks of the encircling wall were allegedly stained with blood, according to a legend about the castle of Alarcón, and odd dark and reddish stains can still be seen between the mortar.

The castle once served as the residence of the region's lord. His sister was quite attractive and suitable for marriage, and she attracted numerous suitors. One of them was the notoriously bad-tempered son of a neighbouring lord; when he made the first move to ask for her hand, he was rudely expelled from the group.

Later, the lord of the castle learned of the spurned suitor's intense animosity and his plots to kill him and abduct his sister. He therefore took great care to prepare the reception when a stranger showed up one day with the aim of meeting him in secret since he believed the man might be planning to kill him.

Once the suspicions were confirmed, the servants killed the stranger just as he was ready to attack the lord by holding him in place and mixing his body with the mortar they were preparing for various construction projects taking place inside the castle.

Alejandro de Alarcón and the Duchess Julia de Alarcón, who both protected numerous people during the country's battles and rose to fame in the area, were in charge of the castle in 1720.

Don Rafael Lázaro Alvarez de Torrijos purchased the castle and "four or five more little towers" from José Mara Bernardino Fernández de Velasco, Duke of Fras, for 20,000 reales (Madrid, 5th June 1863).

The lvarez Torrijos Torres family, who were born in La Almarcha but had a paternal family history in Gascas, were expropriated of it in 1963 by Manuel Fraga Iribarne, Minister of Information and Tourism. It was initially renovated as the Parador Nacional de Tourism Marqués de Villena, and the same minister opened it on March 21st, 1966.