 With the discovery of gold in 1851 ( when the Port Phillip District became the new Colony of Victoria ) , and the resulting influx of population , law and order became more difficult to maintain . Subsequently , a new wing , with its own perimeter wall , was constructed between 1852 and 1854 ; the building using bluestone instead of sandstone . The design was based on that of British prison engineer Joshua Jebb , and especially the designs for the Pentonville Model Prison in London ( which suited the current prison reform theories at the time ) . The new wing was extended in between 1857 and 1859 , with the boundary wall also being extended during this time . In 1860 , a new north wing was built ; which included entrance buildings , a central hall and chapel . Between 1862 and 1864 , a cell block was built for female prisoners on the western side – it was basically a replica of the present east block ( until this time , female convicts were not kept apart from the male prisoners ) . In 1864 , the perimeter wall , and the gaol overall , was completed ; making it a dominant feature of authority on the Melbourne skyline . 
