The site and remains of the Lyttelton Gaol, built in an ad hoc manner from 1857 right in the township of Lyttelton in Oxford Street, incorporate relatively rare surviving examples of early concrete use in New Zealand from the 1870s and are important in informing about New Zealand's early penal system and law and order in the colonial town. Although most of the buildings associated with the gaol have been demolished, some significant features remain as a reminder of the gaol that was for a long time a dominant feature in the town. These include massive concrete retaining walls, concrete steps and part of a concrete block of cells.

The Lyttelton Gaol was the first in the Canterbury colony and is associated with early development of the New Zealand penal system. It was built on this site in an ad hoc manner over several decades, beginning in 1857, by first the Canterbury Provincial Government and then central government. Although the early Canterbury Association settlers wanted to build an ideal society, they quickly discovered that the 'Old World Evils' had followed them to New Zealand. The gaol catered for the mentally ill and debtors as well as criminals. As it was extended over the second half of the 19th century, notably to the designs of architect B W Mountfort from 1871, it became one of the largest prisons in the country and achieved proportions that were huge by the standards of a small town. It is reported that approximately 90% of the inmates of the gaol, at any one time, were British Seamen. The gaol was the site of several events of importance, including seven hangings. It was also a small industrial centre, being the place of manufacture by prisoners of clothing and boots required by both prison staff and prisoners throughout country.

In common with other New Zealand prisons of the day, the Lyttelton prisoners undertook public works as part of their hard labour and contributed to the construction of a considerable amount of Lyttelton's infrastructure (much of the red volcanic stone walls around the town, including extensive stone walling on Oxford Street itself, is attributable to them). The survival of public work gangs until 1915, long after they had been abolished in England, ensured that prisons such as Lyttelton retained a highly visible public presence in their communities. The gaol closed in 1920 after a new prison was built at Paparua, west of Christchurch, and Lyttelton's main gaol buildings were demolished in 1922-24. The site was leased to the adjacent school as a playground.

A key feature of Oxford Street is now the open area that was formerly part of the site of the large Gothic style Lyttelton Gaol complex. Now containing a playground, rose gardens and the 1950s Upham Memorial Clock, remnants of the gaol can be seen in concrete retaining walls and a small block of cells built into the upper slope, historic pedestrian pathways and concrete steps. The concrete is noteworthy for being a relatively rare example of early use of concrete in New Zealand. The Upham Memorial Clock is the townsfolk's memorial to Dr Charles Hazlitt Upham, who came to Lyttelton as a young naval surgeon in 1898 and became a much loved general practitioner who served the community for half a century.

The Lyttelton Gaol site is a significant archaeological site that retains architectural and structural evidence of early concrete use and which reflects an aspect of New Zealand's penal history.