The New Plymouth Prison, also known as Marsland Hill Prison, is a decommissioned correctional facility in New Plymouth, New Zealand, registered as a Category 1 historic place by Heritage New Zealand. Prior to its closure, it was the oldest operational prison in New Zealand, with roots dating back to a wooden military hospital built in the 1850s. The prison is considered a place of high cultural and historical importance due to its association with penal reform in New Zealand, and its layout reflecting 19th-century punishment policies.
The New Plymouth Prison was converted from a 1850s wooden military hospital, originally built on Marsland Hill, the former Maori stronghold of Pukaka Pa, in New Plymouth Central. The hill was the place of the former military barracks, where the British troops were stationed in a stockade, in 1855, during the New Zealand Wars. The hospital cared for the injured imperial troops during the Taranaki Wars, but after the troops withdrew, it was repurposed as a district jail in 1870.
The works to convert the building into a more secure facility started in 1879. The wooden structure was reinforced with iron cladding and cement floors over stone rubble to enhance security. It included cells (mostly for men, with a few for women), kitchen, dining, ablution, chapel facilities, and accommodation for the jailer's family. Prisoners engaged in hard labour, such as breaking stones from a nearby quarry, a practice that lasted until the late 1950s.
The refurbished prison reopened in 1880, with construction continuing into 1904. Minor additions and alterations were made throughout its operational life.
Between 1917 and 1954, the prison was used as a specialised facility for men convicted of homosexual offences, a period now regarded as a failed penal experiment.
In March 2013, the 140-years-old prison was closed because it was deemed an earthquake risk and no longer met modern humanitarian standards for prisoner housing. The Department of Corrections commissioned a Conservation Plan for the site.
Now, the site is owned and managed by Land Information New Zealand (LINZ) while it undergoes the disposal process under the Public Works Act.
The prison is known for its Victorian penitentiary design, its frightening bluestone walls, well-preserved interior evoking a sense of the harsh discipline experienced by its inmates, and the very small cells, measuring approximately 2 metres by 3 metres.
The prison's design reflects 19th-century penal reform ideas by John Howard, emphasising classification and separate confinement to encourage reform and prevent the emergence of a criminal class. Captain Arthur Hume, Inspector-General of prisons, implemented these ideas in New Zealand, leading to the expansion of the prison from 1879 with three separate wings.