Travelers can spend days, weeks, or even months in Rome and not see everything. Unfortunately, most visitors have limited vacation time (and limited vacation funds). If you are planning a trip to Rome, here's some ideas from the About.com Guide to Italy Travel for things to do and see with three days in Rome.
Many travelers to Europe book a Mediterranean cruise in order to see as much of the region as possible in a short time. Dozens of cruise ships sail the Mediterranean year-round, although most are located in the region between April and October. Mediterranean cruise itineraries often embark or disembark in Rome, so cruise passengers can add on a few days before or after their cruise. This will allow extra time to see all the highlights. Cruise ships porting at Civitavecchia in the middle of a cruise may only feature one day in Rome. If so, you will need to choose from the long list of things to see in Rome and then plan to return someday.
One way to help "insure" your return to Rome -- throw a coin in the Trevi Fountain!
Trevi Fountain (c) Linda Garrison