Tivoli is located just 30 km from the center of Rome, and by car it's a 20minute ride if there is no traffic on the road (but who am I kidding, if you have a car in Rome then you detest traffic because it makes you really angry)
Anyway, it's a great opportunity for someone to visit Tivoli during the weekend, because there are big areas that need a lot of hours to devote for exploration.
There are 3 villas in total for you to see:
Villa D'Este
Villa Gregoriana
Villa Adriana
Photo gallery