[7] The building was complete in 1866,[8] but it stopped at the left wing of the main hospital because 20,000 pounds had been spent and this was thought adequate for the community at the time.

Patients were moved from the Auckland Hospital site to the "new asylum" on 8 March 1867 [9][better source needed] After the building was gutted by an 1877 fire, Philip Herapath supervised the reconstruction.

An estimated two-thousand tons of stone was made available in this exercise through detonation of 16 barrels of gunpowder under a 20-foot deep bed of lava, which created a miniature "earthquake" felt in the surrounding area.

A piggery was built in the 1880s and a milking shed, hay store, and farm manager's home were constructed c.1882.

[8] In 1889 a news article reported the asylum had an orchard, dairy, and piggery with 50–60 Berkshire crosses.

Later constructions include accommodation for the medical superintendent in 1909, two auxiliary hospital buildings in 1913 and 1915, and the Penman House in 1930.

The officials of the institution at the time were Robert Martin Beattie, medical superintendent; William Webster, assistant medical officer; Edward Newport, head attendant; Sophia Campbell, matron; and J. D. Muir, farm manager.

[4] Avondale Mental Asylum became Oakley Hospital, it contained a male forensic unit and general psychiatric wards.

[10] Controversial plans were considered for the hospital's M3 Ward to be turned into a medical security prison in 1986.

[6][17] Starting in 2018 Unitec transfer land to the Crown as part of a roughly 40 hectares (99 acres) housing development involving the construction of thousands of homes.

In the central portion of the building were the dining halls, kitchen, and store-rooms, and the two adjoining wings were the male and female wards.

[10] A spring on the estate, and a waterfall on Oakley Creek,[15] was ample for domestic and fire prevention purposes.

A farm, consisting of nearly 200 acres (81 ha), was attached to the asylum, providing for healthful recreation and fresh vegetables.