Once parked, we looked for a tourist information office to grab a city map and get more info about the bus that dives into the river. And we left (horrified if I may) upon discovering that it was €1 for the map and €19 for the bus tour. We walked around for a while and then we decided to go to the Maritien Museum, part of which is on an old warship. It turned out to be an interactive museum for kids (us) and we really liked it, helped by the fact that, due to a harbor festival, this and other museums were free (instead of €6.50).