Look on the website listed above for Rome. The only one in Rome is at the Piazza Barberini. There is none right by the Trevi fountain. Piazza Barberini is about a 10-15 minute walk from the Trevi. Even if you don't want to walk, remember that taxis are very inexpensive in Rome (other than from the airport). If you walk up the road (turn right as you leave the Easyeverything) you will come upon the Palazzo Barberini. It is a great area to wander in too. If you are staying over the river near Vatican City, this would not be convenient for you at all.