Goronga, with farm and other buildings dating from c1889 or earlier, and located in a spacious and notable garden setting, is of State significance as an exceptional example of the gentlemen's residences and rural retreats built in the state's picturesque mountain areas last century.
The complex has historical significance for its associations with Matilda Raleigh, wife of Walter T. Raleigh, grazier, who designed the main house, possibly using a pattern book based on Indian colonial bungalows. The property also has significance for its associations with the Mann family. In 1915, the Raleighs' daughter, Adeline, and her husband, Frederick (later Sir Frederick) Mann, Chief Justice of Victoria, made their home at Goronga. It has remained in Mann family ownership.
The interior of the main house with its stained and lacquered softwood T&G bead edge boarding, all now with a rich patina, add to the significance of the property.
The garden, typical of hill station gardens, with the earliest oaks and conifers dating from the Raleigh ownership, and an old apple orchard at the side of the garden planted by Raleigh, are also of high significance. The garden is of significance to the Cardinia Shire and contributory to both house & property, as a good example of hill station garden.
Goronga house is set on a terrace in lawns fringed by mature garden, at the top of a hill. Two driveways extend back to Mann Road, bordered by mature oaks. Mature trees and the orchard lies to the north and east of the house.
Elsewhere, between Mann Road and the house, is what is reputedly a former church/hall from Mt. Burnett which now acts as an outbuilding to the farm. It is a weatherboarded gabled building, with an added skillion fibrous cement and weatherboard-clad annexe. The roof is corrugated iron. Further north is the gabled weatherboarded former packing shed which dates from the 1920s.
At the rear of and linked to the house is what is thought to be the first house, a single-storey gabled, weatherboarded and verandahed cottage, with an attached brick chimney at one end.
This was initially extended to form a separating room and laundry and has since been renovated to form a flat.
The main house is an attic-style steeply gabled roof house with unusual wall construction. The walls are timber framed and lined internally but the outside is a ruled lathe and stucco finish.
The roof is clad with corrugated iron and there are attic dormers (said to be original) as well as windows in the gable ends. The northern dormers have early diagonal boarded wall cladding but the southern ones have sheet cladding.
The four-sided verandah roof is a continuation of the main roof, flaring at each end of the house to cover the verandah and create a Dutch gable hip form. The verandah posts are stop-chamfered timber sections with some indication of a simple frieze. The gables of the main and dormer roofs have timber finials and the three main chimneys are cemented with moulded cornices and plain entablatures. Openings are full-length French window pairs, with top lights, or windows set in projecting bays under the verandah. These French windows and the verandah give the house an Indian Bungalow or Hill Station character which may be linked with a member of the family known to have served in India. The garden supports this.
The house interior is lined with stained and lacquered softwood T&G bead edge boarding, all now with a rich patina. The upstairs ceilings follow the roof form, with the dormers forming boarded alcoves to each room.
The surrounding exotic landscape includes two oak drives, with some individually important oak specimens as part of these drives and in the garden and orchard. Many other plantings exist including a coronation tree.
This hill station type garden contains a fine collection of mature trees, particularly oaks and conifers. Most of the planting has been attributed the Raleigh family and dates from c1890-1900. The property is entered by a driveway lined with a magnificent avenue of mature oaks (Quercus canariensis?). Mature specimen trees are planted throughout the extensive garden and include a pair of very large bull bay magnolias (Magnolia grandiflora), a variety of cultivars and species of rhododendron in garden beds and around the house, a very large Waterhousea ventenatii, a low hedge of Pittosporum undulatum, pin oak (Quercus palustris), camphor laurel (Cinnamomum camphora), English oak (Quercus robur), copper beech, and Cupressus macrocarpa. Other large and mature conifers include the George VI coronation tree (planted c1937), identified by a memorial plaque just at the base of the tree which is Cupressus torulosa or C. lusitanica, and next to Cedrus deodara. There are also two redwoods, Sequoia sempervirens.
A number of very large oak trees include two Algerian oaks (Quercus canariensis), and a 75 year old oak near the tennis court. Sir Frederick Mann planted the cedar, Waterhousea sp. and many of the cypress in the 1920s. An old apple orchard at the side of the garden is thought to have been planted by Raleigh.
An unrelated balcony, with boarded balustrading, has been added at the south end (replacing a window with new French doors); skylights and polythene tubing (solar heating) have been added to the roof. The verandah of the rear wing has been replaced and the interior altered.
The former church has also been altered internally with some boarding to indicate its former use.