It is run as a joint enterprise between Castle Howard Estates and Royal Botanic Gardens, Kew.

[1] Originating in 1959,[2] it comprises more than 6,000 trees, including some that are rare or endangered,[3] across a site of 128 acres (52 hectares).

[4] The walling to the south of the arboretum was designed by John Vanbrugh, and is in limestone.

The wall is about 4 metres (13 ft) high, it extends for about 1 mile (1.6 km), and has a plinth, buttresses and tapering upper courses.

The wall contains square and circular interval towers of varying designs.