I have a love/hate memory of Rome. The culture, architecture and history cannot be replicated. Highly recommend you do a Walks of Italy tour of the Colosseum & Roman Forum - having someone narrate makes it come to life. Vatican City is also a must do, although a hassle. Book a tour in advance so you can compare prices or else you'll spend literally all day in line. Rome is so large, but we stayed near Roma Termini Station for convenience. We walked most places because the subway is packed.