In 1918 at the end of World War I, control of Stewart House was temporarily handed over to the Wanganui Hospital Board to care for patients of the worldwide influenza epidemic which killed some 6680 New Zealanders. Stewart House operated as a specialist influenza ward for six weeks, caring for scores of sick returned servicemen and locals.
In 1979 the council sold the property to private owners and the proceeds were used to refurbish the Plunket rooms.
The sale is being handled through negotiation, and the agency says while the original property remains largely intact, considerable additions and alterations had been undertaken on the home over the past 90 years.
A lot of the original interior has been altered over time but it includes a games room where a billiard table would once have been, a study, library, a full butler's pantry, six bedrooms and three bathrooms.
Some of the rooms still show the original rimu and matai doors, frames, stairwell and bannister railings and it is likely there is more native wood to be exposed underneath the carpet, or behind layers of paint and wallpaper.
The 32-room home is ranked among Whanganui's biggest and sits on 1486 square metres of land.
Offers are expected in the region of $500,000.