The Christchurch Town Hall was damaged in the 2010 earthquakes and eventually destroyed in the 2011 earthquakes.
On Friday it had a visit from the original architects of the building to check how the rebuild is going.
Fifty years after the original competition was opened to select the designer of the building, architects Sir Miles Warren and Maurice Mahoney returned to analyse its current state.
On Friday the final piece of the original heritage fabric was removed, signalling the half-way mark of the rebuild.
The two and a half tonne acoustic donut was lowered in front of Mr Mahoney.
"It's a bit upsetting, seeing [the building] as it is," he said.
Hawkins Construction's Steve Taw said the rebuild is proving challenging given the conditions.
"Probably the biggest challenge is some of the areas you step in to, there's a lot of work which has to go inside of the building," he said.
"There's a lot of new engineering principles [that] need to be put into the reinstatement or the strengthening of the building.
"We've got limited access in the building [and] there are only so many faces you can work on at one time. There's a lot going on at any one time."
Sir Miles was emotional about the rebuild.
"It's a wonderful feeling to see," he said.
"We were extraordinarily lucky to win the architectural competition for this building and it really [did] set up one's career thereafter."
Both Sir Miles and Mr Mahoney hope the finished product will have the same look and feel that the building always had.
"Those who are old enough, I hope they'll see the way it used to be. And they recognise it and [are] happy to see it and they look forward to seeing it," Mr Mahoney says.
The rebuild is expected to be finished in June 2018.