Why not take the cable car from the Torre Sant Sebastia in Barceloneta to Montjuïc one day? The kids will love the ride and the views of the city and sea. The Port Vell Aerial Tramway connects Barcelona’s old harbour with Montjuïc hill. From there the Montjuïc cable car goes all the way up tot he Castle. When you get to Montjuïc there is loads to do including meandering through parks and visiting museums. On exiting Barceloneta metro station head down Passeig de Joan Borbó and you will see the aerial tramway ahead of you.