Montjuïc Castle is a historic fortress located on top of Montjuïc hill in Barcelona. Built in the 17th century, it offers breathtaking views of the city and the Mediterranean Sea. The castle has played a significant role in the city's history and has been used as a military prison and a strategic defense point. Today, it serves as a cultural center and a popular tourist attraction. Visitors can explore the castle's grounds, visit the museum inside, and enjoy the panoramic views from the battlements.