4. Galleria Borghese
Set in the 17th-century Villa Borghese, this gallery houses the astounding collection of Cardinal Scipione Borghese, the nephew of Pope Paul V and a patron of great artists such as Caravaggio and Bernini. Stroll the grounds, with their lake and English-style gardens, before heading inside to see Titian's allegorical Sacred and Profane Love and Raphael's powerful Deposition, among many other paintings. The marble sculpture of a stern David by a young Bernini is another highlight.