Castle of Sant Boi Monument · Sant Boi de Llobregat, Baix Llobregat, Barcelona Image of Sant Boi de Llobregat, not of the place itself. Castell de Sant Boi, a fortification that gave rise to the town of Sant Boi de Llobregat (Baix Llobregat, Barcelona), built by the Muslims around the year 801; the settlement appears documented in 965 under the Arabic name Alcalà, meaning castle. In 1238 Jaume I granted market privileges to its lord; the estate passed to the Lacera family in 1299 and later to the Marc, Rosanes, Torrelles and Cardona families. In the 19th century it was ceded to the Ramon family, who built a large manor house on the site; the original castle building has not survived. Since the mid-20th century the manor house has operated as the El Castell hotel. It has been declared a cultural asset of national interest (BIC RI-51-0005629, Spain's highest level of heritage protection) since 8 November 1988. Photo: Enric (CC BY-SA 4.0) What to see and do in Sant Boi de Llobregat