The Park of the Monsters, or "Parco dei Mostri," in the Garden of Bomarzo was not meant to be pretty. Commissioned in 1552 by Prince Pier Francesco Orsini, it was an expression of grief designed to shock.
The Prince, also known as Vicino, had just been through a brutal war, had his friend killed, held for ransom for years and come home only to have his beloved wife die. Racked with grief the Prince wanted to create a shocking "Villa of Wonders" and hired architect Pirro Ligorio to help him do so. Ligorio was a widely respected architect and artist and had previously completed the Cathedral of Saint Peter in Rome after the death of Michelangelo, and the Villa d'Este in Tivoli.
When you are in the park be sure to enter the giant screaming mouth, (known as the mouth of hell) inside of which there is a picnic table on the tongue and enough seating space for a small group to have lunch.