Galleria Borghese
If you're into some Italian arthistory you must have heard of this family: The House of Borghese. In their times they were in the center of the power, both in the catholic church as well in the states of Siena and Rome. They collected quite some art during the centuries, a lot of which is exposed in this Borghese Gallery.
Daily opened from 9 till 19h, closed on mondays.