Day 2 was off to another auspicious start - a visit to Vatican City. Again, there is a "Skip the line" ticket, which you can purchase from the official website at a lower fee. I spent about 3 hours here (36 hours only in Rome, remember? ;-) ). So, to be honest, I could not complete everything. Ideally, the Vatican requires one full day - you come in at 8 and you leave at 3pm (or whenever it closes).
Do not miss the Sistine Chapel, which is famous for the paintings of Michelangelo! (Fun fact - did you know that Michelangelo was actually a sculptor and not a painter?) After you come out through the exit, head over to St. Peter's Basilica. It is a gigantic chapel, with beautiful paintings and relics!
Before you exit the Vatican City, take a good look at the Pontifical Swiss Guards, who are the Pope's personal bodyguards!