In the highest part of the built-up area of Palena is the imposing Castle, built on a rocky ridge it seems almost a natural element.
Its existence is documented since the twelfth century, but certainly there have been changes and reconstructions to its original structure, also after partial collapses, mostly due to earthquakes, frequent in the area. Particularly serious were those caused by the earthquake in 1933 that destroyed the towers, the donjon and the belvedere of the castle. During World War II at the damages of previous earthquakes added those produced by bombing. Lords who through the centuries alternated in dominance of territory of Palena lived in the castle: in the fifteenth century the Caldora, Matteo di Capua, later the d’Aquino princes of Caramanico. The castle has a rectangular shape as results from the unification of various building elements, which however appear unified by prospects treated in a similar way, i.e. with a double set of stone-framed windows. Even the covering, with gabled roofs and three rows cornices of overlapped tiles, helps to create the impression of a unified structure. On one side there is a portico with four arches, while on the opposite there are four small arches. The entrance consists of a door with round arch, to which corresponds in the wall behind a portal with architrave and a geometric design cornice. In the Interior of the castle there is the Museum of paleontology of Alto Aventino.