We went to the Vatican Museum to mainly see the Sistine Chapel of course. I had done research prior to our trip and ended up buying our tickets online for a specified time slot. THE BEST DECISION EVER. We arrived and the line (in February!) was around the corner, at least 1 1/2 hrs. With our tickets in hand, we skipped the line, went to the special "online tickets" entrance and waited in the short 5 minute security line and proceeded to the museum. You must walk through the actual museum to get to the Sistine Chapel (About 1/2 hr walk) so we walked rather quickly, stopped only in the Rafaello galleries, before proceeding to the Sistine Chapel. It is beyond words and just breathtaking. From there, we proceeded to St. Peter's Basilica and climbed the dome, which is highly recommended as well. Just beware, its over 500 steps up, but the view is incredible!