Castell Medieval d'Ulldecona is a Spanish Cultural Asset of National Interest perched atop a hilltop in Tarragona province's Terres de l'Ebre region. Originally an Andalusian fortification during the Arab occupation (8th–11th centuries), it was transformed into a Christian castle after 1148 when the Montcada family ceded it to the military Order of the Hospitallers. Documented as complete by 1173, the castle served as a commandery headquarters until the late 13th century when the population relocated to the plain below. Guided tours are offered on select days, featuring views of the distinctive tower on a circular base approximately 10 meters in diameter, preserving key medieval stonework.
