8 places
For good luck, throw three coins into the fountain, using your right hand and throwing them over your left shoulder. The first coin is so that you return to Rome, the second to find love, and third to get married.
Read Raphael's beautiful sarcophagus inscription: "Here lies Raphael, by whom Nature feared to be outdone while he lived, and when he died, feared that she herself would die".
Buy the combo ticket at the Roman Forum first and fly past all the people waiting in line at the Colosseum.
Do not forget to visit Bernini's grave within the basilica, it's on the north eastern part of the hall and it's on the floor.
If you arrive before noon, expect long lines. Come in the afternoon to see a much smaller crowd.
There is a natural spring for drinking just below the Palatino to your west, down the stairs if you're looking at the Palatino from above.
Pay the extra fee to take an elevator up to the top. The views are amazing!
Catch beautiful sunlight inside the cathedral during sunsets. The best time for taking pictures!