Wall and Tower of la Presó Monument · Caldes de Montbui, Vallès Oriental, Barcelona The wall and the Presó tower are remains of the medieval walled precinct of Caldes de Montbui, documented since 1102, whose winding course can still be traced in the town's historic center. The best-preserved part is the defensive tower of one of the town's old gates, reused as a prison, with a ground floor and two upper floors, masonry walls and ceramic-piece vaults, and a flat, walkable roof. The wall, which was reinforced during the Carlist Wars, originally had four gates facing the cardinal points, expanded to five in the 18th century, each with its own chapel. It is declared Bien Cultural de Interés Nacional (Catalonia's highest level of heritage protection). Photo: El senyor dels Bertins (CC BY-SA 2.0) What to see and do in Caldes de Montbui