The fortification is found at the top of a hill in which ceramic remains from the Bronze Age and Iberian Age have been excavated. The Arenós Castle, however, is of Isalmic origin. The first written mention appears in a Teruel charter from 1177.
Belonging to the Almohad King of Valencia, Zayd Abu Zayd, who was governor of the Alto Mijares region after the conquest of James I of Aragon. Converted to Christianity, the castle was given as a gift in the wedding of his daughter Alda with Blasc Ximénez de Arenós, son of Ximén Perez de Arenós, knight and lieutenant of the Aragonese King, who gave them the title of barons of Arenós Two centuries later, in 1464, the monarch John II of Aragón confiscated the barony from James of Arenós, due to an confrontation between the two, and gave it, with the title of Villahermosa del Río, to his son Alfonso. Arenós, however, tried to resist with arms in 1476.
Currently, the Arenós Castle finds itself in quite a deteriorated state. It is possible to see two chambers, with Islamic and Christian remains. The upper chamber is found in the top of middle of the hill, above a platform of protruding rocks that have been adjusted with masonry to give it a rectangular shape. In this space, a semi-circular tower rises, with arrows. At the other end, there is a second tower, square, partially outdated and made with angular masonry and brickwork. Both towers are united by curtains
Below, there is the wall of the lower chamber, next to the rocky platform. The tower stands out with a square base, the best preserved, with battlements, oriented southeasterly, with two cisterns and some curtains, also with crenellations, made from tapestry.