275px|thumb|Willoughby Municipality
Castle Cove is a suburb on the lower North Shore of Sydney, in the state of New South Wales, Australia. Castle Cove is located north of the Sydney central business district, in the local government area of the City of Willoughby. Castle Cove is situated on the western side of Middle Harbour.
History
The Cammeraygal people of the Guringai nation lived in the area until the 1820s and are recorded as being in the northern parts of the Sydney region for approximately 5,800 years.
It is believed that Castle Cove was named after the estate of Henry Hastings Willis, a prominent member of the Parliament of New South Wales at the time.
In 1858 the first grant purchase was made to Dr H. G. Alleyne. By 1878 almost all the land on the peninsula had been sold. In 1886 most of the area had been resold to Andrew Armstrong who formed the Cammeray Estate Land Company, which went into liquidation in 1893. In 1903-04 the Willis family built "Innisfallen Castle", a grand, castle-like house. They had purchased from Dr Alleyne on a default mortgage and used the land for light farming.