Citavecchia to Tarquinia by train

The Civitavecchia train station is across the street from the seashore over one mile from the port (the exact distance depends on where exactly the cruise ship shuttle bus drops people, which I don’t know). In any case plan on 20 to 30 min walk in case the line at the taxi stand is too long.

Once at the station purchase a ticket to Tarquinia. Regional trains are the only ones stopping at Tarquinia. Remember to validate the ticket (date stamp at the machine) before boarding. The train ride is very short, a little over 10 min.

Once at the Tarquinia station, there are buses to the old city center on top of the hill. Info below.
https://tarquiniaturismo.it/en/tourist-information/

The train info is below
www.trenitalia.com

I noticed that there are few trains in the morning after 7:30 (there is only one bus at 9:40 and one train at 11:15, then one at 1:15pm) therefore you might consider sharing a taxi to Tarquinia going (20 min drive) so that you can get to the Etruscan Necropolis and the Etruscan Museum as early as possible. Tarquinia’s Etruscan Necropolis and the Museum is one of the most important in Italy. The Necropolis in on the west side of the town, just out of town, while the museum is in the historical center. They are walking distance. Ask the taxi to take you to the Necropolis first.

Thanks for the info. Any ball park estimate of cost of a taxi to Tarquinia and do you arrange ahead of time or just get
an available one when we arrive?

Although it's not necessarily "slow", note that you can't walk around the piers at Civitavecchia. You have to take the proprietary free shuttle bus to the port-bus shelter circle beside the town. One reason I mention it is that when we were checking in at the last minute for our cruise (I mean, like someone on an independent excursion rushing back to the ship ... .... ) we had to board a bus that was going to serve three different ships for three different cruise companies, and sit on the hot bus for what seemed like 20 minutes until it was close to full. So don't "plan" to return 30 minutes before the ship sails without you. Especially because the Civitavecchia rail station is (opinion) quite far from the bus shelter circle. Maybe Google Maps can be helpful here.

I don’t know the prices for taxi to Tarquinia. Based on distance I would say no more than €40-€50.
I presume that there will be hordes of cruiseiders trying to get taxis upon disembarking therefore it might be a better idea to book something ahead of time.

I found this taxi and limo company based in Civitavecchia that might help. All contact info is in the website:
https://www.taxicivitavecchia.com
They also offer excursion packages for cruise travelers. I see they have one that focuses on the Etruscans that includes both Tarquinia and Tuscania, two of the most important Etruscan centers. It lasts 6 hours. Inquire with them and if the price and the timing works for you it might be worthwhile.
https://www.taxicivitavecchia.com/shore-excursions/

Thank you both.