Whippany Farm is located at 53 E. Hanover Avenue.
The Boston architects Arthur Rotch and George Tilden designed this Colonial Revival mansion as a summer home for George Griswold Frelinghuysen and his wife Sara Ballantine. The house was completed in 1892 and surrounded by a pastoral landscape of sweeping lawns, woods, and gardens.
George’s daughter Matilda kept the summer home and in 1964 planned its conversion to a public arboretum. She bequeathed the estate in 1969 to the Morris County Park Commission, which occupies the house as its headquarters. The former carriage house contains the Frelinghuysen carriages.