Things to see in Naples:
1) Caravaggio: Martirio di Sant’Orsola. The best Caravaggio painting of the three they have in Naples.
2) Caravaggio: Flagellazione di Cristo. Much better in real life than any other picture you will see around.
3) Caravaggio: 7 opere di Misericordia. Gives a better impression from the museum balcony.
4) Archaeological Museum: visit this at any cost! Perfect mix of paintings, statues and mosaics which will leave you in a state of ecstasy.