Marseille
Chateau d'If - Visit the "steep rock on which stands the frowning Chateau d'If," made famous in the novel by Alexandre Dumas, The Count of Monte Cristo. You too may feel cut down to size when you enter this "this strange pile, this prison whose very name spelt terror." Catch the boat to the Chateau d' If from the quay at the end of the Old Port, and fortunately, there is a return trip.
Vieux Port - Walk around the Old Port and take the charming, small size ferryboat from one side to the other. The Vieux port is also a spot to watch small boats coming and going and plenty of cafes and restaurants to sit down and relax.
Parks - Marseille has a number of lovely parks. Visit the Cinq Avenue de Longchamp Park, across from the Palais Longchamp. This park has pony rides and a playground for little kids. The Parc Borely has boating on the lake.
Archeological Garden (Jardin des Vestiges) - Run around the grass and stone ruins of the old harbor of Marseille. Imagine the port of Marseilles (and the oldest city in France) in the Roman era.
The Calanques - Take a four hour boat ride on the sparkling blue Mediterranean to see the steep rocky coastline," les calanques." Kids will love the shapes of these amazing limestone cliffs, like so much sculpture, and the clear water.