Musée Océanographique

Stuck dramatically to the edge of a cliff since 1910, the world-renowned Musée Océanographique - a Prince Albert I (1848-1922) creation - is a stunner. Its centrepiece is the 7.5m-long coral reef, with vivid tropical fish on one side and deep-sea predators on the other. Ninety smaller tanks contain a dazzling 450 Mediterranean and tropical species, sustained by 250,000L of freshly pumped sea water per day.

The Whale Room, filled with cetacean skeletons and pickled embryos, and fanciful seabird-covered chandeliers, mosaic floors and oak doorframes carved into marine shapes at every turn complete the mesmerising ensemble. Kids will love the tactile basin; tickets for the 30-minute feel-the-fish sessions are sold at the entrance.

Finish with a cup of tea in the aquarium's rooftop brasserie.