I wrote another post for mTrip entitled Rome in film which talks about three films that were shot in Rome: Mamma Roma, La dolce vita, and the American film, Roman Holiday (starring Gregory Peck and Audrey Hepburn). All three films are excellent examples of varying cinematic styles, with the first two films by Italian directors and the last by an American one. The post can be read here:
The post is an appropriate once since the 5th edition of the Rome Film Festival (Festival Internazionale del Film di Roma) started yesterday in Rome. All three films are available commercially from Amazon.com and many other online retailers or through Netflix or Blockbuster online.