A ceremony will take place on Spike Island later today to mark its formal handover from the Prison Service to Cork County Council.
It is hoped the former prison, which dates back to Cromwellian times, can be transformed into a major tourist attraction.
The raising of the Irish flag today will mark the 72nd anniversary of the transfer of Spike Island from British to Irish control.
Spike Island was the last place that thousands of Irish convicts would have seen before they were dispatched to Van Diemen's Land (Tasmania).
A military outpost or penal institution of some kind since the 16th century, Spike Island closed as a prison in 2004.
The first visitors could be brought to Spike within weeks.