Built in the 12th century in mudejar style, the Castilnovo castle is conserved in good condition. It has a rectangular plan, with six round and square towers. It was rebuilt in the 14th - 16th centuries and again between the 19th and the 20th centuries. The present castle is thought to have been built on a previous structure, probably a small fortress. Trapezoid ground plan, with six round and rectangular turrets of brick and masonry. Arched, parted windows. Rectangular turrets, one if which leads inside the building.
Particularly noteworthy is a corner turret reminiscent of another turret in Monteagudo de las Vicarías. The main features of the building are 14th century.The southern section, with its wooden gallery, dates back to 1861, and the present stone yard was built in the 20th century.
References:Rosenborg Palace was built in the period 1606-34 as Christian IV’s summerhouse just outside the ramparts of Copenhagen. Christian IV was very fond of the palace and often stayed at the castle when he resided in Copenhagen, and it was here that he died in 1648. After his death, the palace passed to his son King Frederik III, who together with his queen, Sophie Amalie, carried out several types of modernisation.
The last king who used the place as a residence was Frederik IV, and around 1720, Rosenborg was abandoned in favor of Frederiksborg Palace.Through the 1700s, considerable art treasures were collected at Rosenborg Castle, among other things items from the estates of deceased royalty and from Christiansborg after the fire there in 1794.
Soon the idea of a museum arose, and that was realised in 1833, which is The Royal Danish Collection’s official year of establishment.