Bomarzo is a small town near Viterbo in the Cimini Hills, Lazio, central Italy.

It is the fief of the Orsini family whose castle is at the edge of the town.

The castle's gardens were created by Pier Francesco Orsini, Duke of Bomarzo , who was born in 1528 and lived until 1588. He was a patron of the arts and devoted his life to the happiness of his wife Julia Farnese .

After her death, he was spurred on to create the gardens, naming them Bosco Sacro, the Sacred Grove or Bosco dei Monstri, the Monsters' grove. The reason for this bizarre name is the many larger than life statues which populate this predominantly barren landscape. The design has been attributed to Pirro Ligorio, a well known architect of his day, he was working 35 miles away in Rome, on the complex around the Villa Giulia, at the time, so he could be responsible for the garden but it is very much out of his style. However, Ligorio could very well be the architect of the small classical temple-like chapel in the garden. This open colonnaded structure is surmounted by a small domed tower.

To describe the garden as a garden is almost a misnomer; this garden contains no pretty flower beds, sweeping lawns or refreshing fountain, instead one of Hannibal's elephants, larger than life, mangles a Roman soldier, a vast mermaid lounges incongruously on the bare ground - a vase of verdure perched on her head. Shelter from the blazing sun can be obtained by climbing a flight of steps into the mouth of a grotesque Giant's head carved from the living rock.

The many monstrous statues appear to be unconnected to any plan and appear to have been littered and placed unceremoniously about the area. The reason for the layout and design of the garden is largely unknown, perhaps they were meant as a foil to the perfect symmetry and layout of the great Renaissance gardens nearby at Villa Farnese and Villa Lante.

During the 19th century and early 20th century the garden became overgrown and neglected, in the mid 20th century a program of restoration was implemented, and today the garden is a major tourist attraction of the locality.

The surreal nature of the garden greatly appealed to the great surrealist Salvador Dalí who discussed this garden at great length. Whatever the reason for its conception it is one of the most amazing sights, offering simultaneously the thrill of the startling with the unexplainable.