Rome is a big city but in the centre, the distances between the most important sites and monuments are not unmanageable so try to move around on foot as much as possible. In this manner, you can adventure down the alleys and small streets and make thousands of new discoveries.
After walking, biking is the next best method for moving around the city. You can go wherever you want without being stuck in traffic and with a bicycle in Rome, you can go everywhere. You can go to the centre and the areas closed to traffic, in Villa Borghese… and that’s not all. You can also travel along the bicycle paths that cross through many of the central locations of the city and even leave the city to see some outlying natural areas. Discover it all by pedalling and breathing fresh air.
http://www.assessoratoambiente.it
There is a new, very easy system for renting a bicycle in Rome. Take a bike from a Bike Sharing parking area. Use the bike as much as you like and when you have finished riding, leave it in another Bike Sharing point. In every parking area, you will find a map of the area as well as the indications for all of the stations, the rules, and information. For more information, go to one of the PIT locations in the city (tourist information point), where you can register, leave a deposit and pick up a smart card to use the service. The service is active from 7am until 11pm. The first half hour is complimentary and then you pay only for the time that you use it.
http://www.roma-n-bike.com
The underground is the most common method of transportation in the city. In Rome, there are two lines that cover the most important and most visited tourist parts of the centre.
Line A, which is orange, passes every 3-4 minutes and takes you, for example, to San Giovanni, Piazza della Repubblica, Piazza Barberini, Piazza di Spagna, Piazza del Popolo and the Vatican. Line B, which is blue, passes every 4-5 minutes and takes you, for example, to Via Cavour, the Colosseum, Circus Maximus, the Pyramid of Cestius and Eur. Both lines have the following service hours: from 05:30 am to 11:30 pm Monday to Friday and until 12:30 pm on Saturdays.
http://www.roma.atac.it
The bus network is very extensive and covers the entire city. There are three types of buses which are identified by three different symbols. The Express (X) line covers long distances and makes few stops, the City (U) line covers shorter distances and makes many stops and the Esatte (C) line goes to the outlying areas at a specific time. After midnight and until 6 in the morning, there are the Night lines (identified by an owl). Among the bus lines, there are some that you can use as though they were tourists buses because they travel to the main monumental locations in the city. These are bus numbers 60, 62, and 64. Also, you shouldn’t miss a complete journey on the mythical 3, a nice tram rail ride that you can pick up a piazza Thorvaldsen. It offers a very interesting ride through the city, visit http://www.roma.atac.it to find out more.
If you don’t have a lot of time and want to get a quick idea of the places in Rome that you can calmly visit later, you can find many double decker, open top Tourist Buses. These buses travel to the most famous sites of the city from Imperial Rome to Christian Rome. Furthermore, they allow you to get off, walk around and then take a later bus with the same ticket.
These tourist buses depart from Termini Station frequently every day. On board, there are hostesses and headphones with audio guides in various languages. Among the various journeys that you can choose, there are two that you shouldn’t miss: the famous 110 open tour that makes a 2 hour trip around the city and the Bus ‘n boat tour with which you can a hop on hop off tour Rome and take a boat ride on the Tiber.
http://www.trambusopen.com
The boat lines (battelli di linea) operate like a bus. They make various stops and have two end points: the Duca d’Aosta bridge (Ponte Duca d'Aosta) and Tiber island (isola Tiberina). The tourist boats (battelli turistici) offer several possibilities: a guided cruise that begins at the pier of Castle Sant’Angelo (Castel sant’Angelo) and lasts for a little over an hour (everyday except Mondays); or a tour of art and nature with a visit to the excavations at Ancient Ostia. This tour departs from the pier of Ponte Marconi (Fridays, Saturdays and Sundays only) and lasts from 9am until 4 pm: http://www.battellidiroma.it