This was the largest building in the prison area of the compound. It consisted of a central tower, with five radial wings.
Adam notes that the designs were sent to London for approval in 1858:
It was December 1858 that the designs, attached to the despatch below, were first sent to London for approval.
CO 129/69, pp 614-620 [from: 1858-12-29 to: 1858-12-29]
Document: PLAN FOR THE EXTENSION OF VICTORIA GAOL
Microform: HKU 2507093
Send to: LYLTON
Encl: ENCLOSURE=3 *PLAN FOR THE EXTENSION OF VICTORIA GAOL WITH LETTERS OF THE SURVEYOR GENERAL IN EXPLANATION.
Keyword(s): PLAN, EXTENSION, VICTORIA, GAOL, SURVEYOR GENERAL,
The building was completed in the first half of 1862.
I've set up the different components of this building as separate Places, as they were demolished at different times. I've set all their completion dates to 1862, but as Adam notes, they may also have been finished at different times:
It was a big project and I think would have opened gradually, block by block. Secondary-sources (the usual suspects) give various dates from 1862 to 1867. Primary sources are harder to come by, especially as newspapers and govt. dept. reports for that period are harder to come by than usual (there may be something in Blue Books). And I guess a gaol was unlikely to have had a grand opening in those days. And of course, the gaol itself was a work in progress pretty much up until the time it closed as such in 1937.