Tibidabo, high, offers striking views over the city and is topped by the Torre de Collserola, a telecommunications tower that is visible from most of the city. Barcelona is peppered with small hills, most of them urbanised, that gave their name to the neighbourhoods built upon them, such as Carmel (), () and Rovira (). The escarpment of Montjuïc (), situated to the southeast, overlooks the harbour and is topped by Montjuïc Castle, a fortress built in the 17-18th centuries to control the city as a replacement for the Ciutadella. Today, the fortress is a museum and Montjuïc is home to several sporting and cultural venues, as well as Barcelona's biggest park and gardens.