The major upgrade of the Durie Hill elevator entrance as well as a maintenance overhaul of its lift car is set to begin.
The elevator will be closed to the public for around 12 weeks from February 15.
"While the council owns the site, the Whanganui Regional Heritage Trust initiated the new entrance in the lead-up to the elevator's 100th birthday celebrations in 2019 and then undertook the design and fundraising," Whanganui District Council's property general manager, Leighton Toy, said.
The council is managing the demolition and build, plus maintaining the elevator at the same time.
Trust member Bruce Falk initially led the project, along with fellow trustees Mary-Ann Ewing and Ann McNamara, but died in 2019.