The building consists of two perpendicular naves preceded by a double gallery with semicircular lowered arches. It was designed during the first half of the 17th century.
The museum has also a collection of metal works and paintings. Inside the art gallery stand out 6 oil paintings on panel painting from the 16th century. These are original works of Hernando de los Llanos, a painter who was a disciple of Leonardo da Vinci. Another work worthy of mentioning is the oil on canvas Curación de Tobias (the healing of Tobias), made by Rafael Tegeo from Caravaca, who was a personal painter of Queen Isabel II and one of the best Spanish neoclassical portraitist from the 19th century.
In the metalwork section we can find the artwork Custiodia-Ostensorio de la Cruz (The Custody-Hostensory of the Cross) from the beginning of the 16th century; the artwork Portacruz de los Baños, a present from Luis Fajardo, the second Marquis of Velez; and the silver gilt box, donated towards the end of the 14th century by the master of the Order of Santiago, Lorenzo Suárez de Figueroa.
Standing as an important piece in the museum, La Casulla de Chirinos, a Muslim tiraz adapted to the shape of liturgical ornament, is believed to have been carried by priest Chirinos at the time of the miraculous apparition of the Cross.
Additionally, the older part of the castle has recently become open to the public, after a recent excavation, where you can now visit the old dungeon.