Wellington's central library will be closed indefinitely from 8.30 tonight.
Engineers have found earthquake safety issues to do with its pre-cast concrete floors.
It follows new assessment guidance from MBIE, after Statistics House partially collapsed in the Kaikoura earthquake.
Mayor Justin Lester says public safety is the number one priority.
"While it's painful to make this decision, it is the only course of action we can take."
He says the library building's footprint will be fenced off.
"We will redirect the footpath around the outside by removing some car parks. There is no risk to anyone around the perimeter of the building."
Wellington City Council's Chief Executive Kevin Lavery told Larry Williams that the building can be repaired, but it will be "years, not months" before it is repaired.
"It was a heart breaking decision to have to close the building at short notice."
He says it is one of Wellington's busiest buildings, with over 3,000 visitors a day.
"We've seen other buildings such as Statistic House that were damaged in the Kaikoura Earthquake, so we felt morally we had no other choice."
Lavery says that library customers will have to rely on the branch network and digital services, but some pop-up libraries and new facilities will come about within several months.
The cost of the repairs is not yet known.