How long is a taxi ride between FCO airport to downtown Rome?
I think the answer would turn on the time of day. Do you need a taxi? There's a train from the airport.
Depending on where you're going and the time of day, average about 40-45 minutes by cab.
You can take the train directly to the termini station in about half an hour. It now costs 14 euros but is direct and saves time and money. It may not be the best solution if you have a lot of luggage.
Donna