Yesterday, we took a funicular (not pictured, unfortunately) and a cable car up to the Monjuïc Castle fortress. It's an impressive structure with excellent views of the city and there's an active park on the surrounding grounds, but it has a dark history. On multiple occasions, its cannon have been turned on the city below to administer collective punishment for resistance to the crown in Madrid. The fortress has also been the site of numerous atrocities. Look up the Bombardment of Barcelona (1842) for example.