Castillo de Biel stands on a rocky platform in the Cinco Villas region of Zaragoza province, a rectangular stone tower dating to the era of Sancho III the Mayor of Navarra, with the first documented tenant being Blasco Orioli between 1042 and 1051. King Sancho Ramírez granted it as a dowry to his wife Felicia of Roucy in 1071, positioning it alongside Uncastillo and Luesia to guard passage through the Sierra Carbonera from Ejea toward Aragon. The monumental complex combines the keep with the 11th-century Romanesque Church of San Martín, reconstructed in the 16th century, creating a unified ecclesiastical and military landmark at 760 meters altitude overlooking the Arba River headwaters.
