Arts Centre Market Manager Shelley Erskine said the rebuild was a part of the Arts Centre restoration project, estimated to cost $255 million.
Two thirds of the tower fell to the ground in the 2011 earthquake.
The project is being funded by donations, grants and community fundraising.
According to a media release on the Arts Centre's website, deconstruction of the tower began in 2019. It took six to seven weeks to complete. Six stone masons this month began restoring the basalt and limestone on the tower's exterior.
The new tower will function as the entrance to a boutique hotel, aiming to be opened by April 2022.
Arts Centre stone mason Darren Blair said the boutique hotel would bring people to the "heritage pocket".
Tessa Peach, who owns the Frances Nation store at the Arts Centre, was looking forward to the restoration and the increase in tourists it could bring.
The completion of the observatory tower, engineering, biology and physics block will mark the end of the second stage in the restoration project.
