Lording it over the small town of Ariccia, this 17th-century palazzo was designed by Gian Lorenzo Bernini for the Chigi family. Its interior, used by Luchino Visconti as location for Il Gattopardo (1963), is divided into a Piano Nobile (noble or main floor; visitable by guided tour only), Cardinal's Rooms, and a small museum dedicated to the Roman baroque. Each has slightly different opening hours so check the website for details.
The main building is surrounded by a 28-hectare wooded park (Parco Chigi). This is closed to all but guided tours – see the website for details – but if you get the chance, it is worth visiting. It was popular with tourists on the Grand Tour in the 18th and 19th centuries and boats some wonderfully romantic corners.