Ostia Antica was a port city and thus important commercial centre of ancient Rome. The site is similar to Pomepi in that it offers a vivid experience of Roman city life. Ostia Antica has the advantage of being less crowded and easily reached from Rome. The ruins of the Ostia Antica are spread over a large area and you can visit the commercial, residential and recreational parts of the town at your leisure. There is a museum and a cafeteria on the site.
To get there take the metro from the Colosseum to the Piramid and change station (follow signs to Ferrovia) and take the Roma-Lido train using the same metro ticket.
For Rick Steves excellent write-up on Ostia Antica see http://www.ricksteves.com/plan/destinations/italy/ostia.htm
Open Tue to Sun from 8.30 to 18.35 (or 1 hour before sunset in winter). There is an admission charge (€ 4.00 in 2005). Call 06 5635 8099 for up to date information.Tivoli
Tivoli which sits on the edge of the Sabine Hills to the east of Rome has been a popular retreat for Romans since ancient times. There are two main sites to see in Tivoli: Hadrian's Villa and Villa D'Este.
To reach Tivoli using public transport, take the Metro from the Colosseum to Ponte Mamollo and then the Cotral bus (every 10 minutes) to Tivoli.
In 117 AD emperor Hadrian build the largest and richest villa in antiquity covering over 70 hectares on which he recreated his favorite monuments and places he had seen during his many campaigns and travels.
Open daily 9.00 till 1 hour before sunset. There is an admission charge (€ 8.50 in 2005). Call 0774 382 733 for up to date information.
This sumptuous Villa was built in the 1550's the exiled cardinal Ippolito (son of Lucrezia Borgia). The palace is covered with frescoes typical of renaissance mansion. It is particularly famous for the terraced gardens with its many baroque fountains.
Open Tue to Sun from 8.30 to 18.45 or 1 hour before sunset in winter. There is an admission charge (€ 6.50 in 2005). Call 0774 312 070 for up to date information.
Naples is a colorful but chaotic charm of south Italy. Pompeii is famous for its ruined city which was frozen in time when Vesuvius erupted in 79AD.
It will require at least six hours travel to and from Naples & Pompeii, and a day trip will therefore be quite long. It is possible to do this day trip with public transport or by tour coach.
Pompeii archaeological site is open daily from 8.30 to 17.00. There is an admission charge (€ 10.00 in 2005).
Florance is the birthplace of the renaissance and there are many things that you can take in even on a day trip such as the Duomo, Michaelangelo's David and Ponte Veccio.
It takes 3.5 hours from Rome to Firenze by rapid train, so a day trip will be long any tiring.