Go a 3 hour tour of the Colosseum, Palatine Hill and the Roman Forum
Visit the Pantheon, one of the free attractions in Rome
Throw a coin at the Trevi Fountain
Visit the Spanish Steps and the Square of Spain
Visit the Vatican City highlights like the St Peter's Basilica, Sistine Chapel and Vatican Museums
Wander through a neighborhood like Monti
Try different delicacies in Rome