Nothing special, worth at trip on the city tour bus from the port and get off in the middle of the city. Worth walking back to the ship through the back streets. Pretty much the same as a lot of European cities.
Again don't waste money on an excursion. Come off the boat an dwalk for 10 minutes to the station. 14.5 Euro return for 2 into Rome on the train. Get of at St Pietro station and take 5 minute walk to the Vatican. Wonderfull city to see, but get a map before you go.