Rome is about the architecture and the food, but you can get lost alone, so if you like to seek out off-the-beaten-path secrets, consider a guided walking tour. If you have just a little time, hit the obvious landmarks: the Coliseum, Piazza Navona, Piazza Colonna, the Borghese Gallery and Museums, Castel Saint Angel, Trevi Fountain, and the Spanish Steps. In fact, the Spanish Steps are one of the great meeting spots in the city, and all around it, you can find a peculiar Roman shopping idiosyncrasy: small artisan shops selling a rainbow of leather glovesworld class in quality and a must-buy if you've got the souvenir budget.
Of course, the main attraction in Rome is actually its own entity: Vatican City (The Holy See) is a state within a city, with only approximately 800 residents but millions of annual tourists. Many are Catholics, but you don't need a religious affiliation to appreciate the beauty of the Sistine Chapel, St. Peter's Square, or the Roman Necropolis.