Filmed at Greystone Mansion in Beverly Hills, California. Two years after this film was made, The City of Beverly Hills purchased the mansion in 1965. It was made into a public park in 1971. Tours are available from 10am to 5pm. Look online for dates and times.
Greystone mansion was also used in The Loved One, in which one portion of the grounds appeared as the swimming pool where John Gielgud's character hangs himself, and one of the property's garden walkways "portrayed" Poet's Corner in the massive cemetery called Whispering Glades.