Easy take the open top tour coach of the city which also goes 5 or six miles up the coast along a very picturesque route. Also visit Napoleans birthplace or simply stroll around this compact and tidy city. It's so easy the ship docks right in city centre and you can wander off and stroll anytime you like.
Very easy to DIY - Try google and 'cruise ports call boards' - the first result will give you all the info under the Europe section
If you like shopping, then this port has one of my favourite pedestrianised shopping streets which runs parallel behind the first main road from dock. Up the hill and to the right there is a small but nice beach area.
Sorry correction the beach is to the left.