Arcos de Jalón Castle, dating from the 14th century, stands on the site of an old Arab fortress. It was besieged in the 14th century by the supporters of the Castilian King Pedro I, who fought against the rebel D. Fernán Gómez de Albornoz, supporter of his bastard brother Enrique de Trastamara.
This castle has a rectangular floor plan although it is quite irregular due to the fact that it adapts to the rugged land of a high and narrow hill that divides the town into two parts. A robust keep is attached to the castle walls which are made of thick stonework, horizontal brick rows and ashlar with stonecutter’s marks on the corners. There is only one entrance which is located high up and two loophole windows.
Inside there are remains of the structures that divided the tower, which once was taller, into different floors, and all throughout the perimeter, you can see where the foundation walls began and some towers that reinforced the structure.
This fortress is so unique due to the double-lined brick walls, a technique that mainly had a structural purpose, but has also given the castle beautiful reddish lines between the stonework. This construction method has a clear Mudejar origin which was most likely influenced by the amount of Muslims in the village and in the area of Aragon.
References:The Broch of Clickimin is a large and well preserved, though somewhat restored broch near Lerwick. Originally built on an island in Clickimin Loch (now increased in size by silting and drainage), it was approached by a stone causeway. The water-level in the loch was reduced in 1874, leaving the broch high and dry. The broch is situated within a walled enclosure and, unusually for brochs, features a large 'blockhouse' between the opening in the enclosure and the broch itself. Another unusual feature is a stone slab featuring sculptured footprints, located in the causeway which approached the site. Situated across the loch is the Clickimin Leisure Centre.