Monthuich Castle (Castillox Montjuich). Barcelona Spain & Monthuich Castle: Located at the commanding height of Monthuich Mountain, you can see the whole view of the port and the city. The castle was first built in 1640 but was destroyed by Philip V in 1705. On its ruins was the present Bourbon military fortress. During the War of Independence, it was occupied by Napoleon and served as a prison during the Civil War. Monthuich Castle witnessed many social movements that suppressed Barcelona and Catalonia. The castle is now partially converted into a military museum.