No one is really sure where Carbonara comes from. Some say the pasta dish made with eggs, pancetta (or guanciale) and cheese was created by the carbonai, or coal workers, because it's a simple, cheap dish. Other say it was created after World War II for American soldiers who yearned for their bacon and eggs.
Whatever the case, if you're in Rome, you must order it at least once. On a recent visit, I tried to eat carbonara at every restaurant I visited. The best I had was at Da Enzo. Located in Trastevere, Da Enzo is popular with locals and off the radar for tourists. Which is always a good sign.