What is the best way to get from City Centre in Rome to the Port of Civitavecchia?
This is a question that has been frequently asked. Using the Search bar will yield numerous threads: https://search.ricksteves.com/?button=&date_range=2y&filter=Travel+Forum&query=Rome+to+Civitavecchia+&utf8=%E2%9C%93
TLDR? : a car service wll be the easiest way. Rome Cabs (not cabs, but private car/drivers) has often been mentioned. You can also find info on the Cruise Critic website, within the Ports of Call forum
The least expensive way is the train and then walk a good way or get a taxi. We've done that, but we cruise with only carry on luggage. If you have more luggage than that, it will not be easy to handle it on the train. I could be wrong, but I remember the train station at the port having some starirs.
The best way, as mentioned above, is a private car service. We've used Rome Cabs a number of times from the airport to Rome, and back, and have always been pleased.
Check with the cruise line to see if they offer a shuttle bus from the city to the port. I know they do from the port to the city at the end of cruises.