Castillo de Sisamón is a medieval fortress located in the small municipality of Sisamón in Zaragoza province, Aragón, strategically positioned on the disputed frontier between the kingdoms of Castile and Aragón. The castle gained prominence during the fourteenth century, particularly during the War of the Two Pedros when its garrison was reinforced to defend against Castilian threats. In 1357, King Pedro IV granted the castle as a lordship to the powerful Heredia family, relatives of the Grand Master of the Hospital. The fortress served as an important frontier defense, maintaining its strategic significance throughout the medieval period. The castle remained under noble control through subsequent centuries, eventually passing to the counts of Contamina in the seventeenth century, and stands today as a testament to Aragón's medieval military heritage.
