An old military fortress that dominates Montjuïc hill in Barcelona, Castell de Montjuic is a 17th-century castle that used to serve as a military base and even as a prison. Nowadays, it is a museum that you can visit while exploring the steep hill and park of Montjuïc. This cultural site often hosts concerts, seminars, and exhibitions. The views from the castle are simply amazing.
Castell de Montjuic is recognized in Hoptale's First-Time Visitor Guides as one of the top things to do in Barcelona.