Montjuïc has been home to the city’s botanical gardens since 1930, but building and access work for the 1992 Olympics threatened their stability to such an extent that it was decided to create a new and improved version up the road; today’s Jardí Botànic. What remains of the original gardens, the Antic Jardí Botànic, can still be visited at Avinguda dels Muntanyans (near the palace), where you’ll find the tallest trees in Barcelona. Also located on Montjuïc is the Mossèn Costa i Llobera garden, on the side of the mountain facing the ferry port. This has Europe’s most complete cactus collection, with over 800 species.