A multi-million dollar restoration on Auckland Art Gallery's heritage building will begin later this year.
Auckland Council's economic and cultural agency, Auckland Unlimited, said the project to fix up the 134-year-old building could take two years to complete.
The project is likely to cost between $10 million and $12m and will repair the deteriorating roof, windows and facade.
Auckland Unlimited said in a statement that restoration had to be expected after a building had weathered more than a century.
"There has not been a sudden failure, but rather progressive deterioration. This has now reached a point where certain areas need comprehensive attention."
Slate roofing needed to be replaced because falling slates posed a risk to the public, it said.
The artworks were not at risk because the roof was "not leaking at this point".
Alterations will be made to reduce condensation from sealed-off wooden windows and the facade will be painted.
Work will begin in the second half of this year.
Areas on the top floor are likely to be closed during the repairs but many parts of the gallery will remain open.