In April, the Arrowtown Post Office's100th birthday will be marked and celebrations planned as part of the 2015 Arrowtown Autumn Festival.
Lakes District Museum director David Clarke said the post office, built during World War 1, was the second in the town.
The first was demolished after the postmaster's house burnt down.
While the original post office remained for a time, after the postmaster's house was rebuilt in 1908 it was decided to establish a new post office on vacant land next door.
The museum purchased the postal agency in 1991 and when New Zealand Post pulled out of Arrowtown in 1995, the museum bought the building for a below-valuation $175,000.
The Queenstown Lakes District Council contributed $40,000 from a land sale, the museum contributed $50,000 and the remaining $85,000 was raised by residents.
An annual market day, held between Christmas and New Year, continues to raise funds for the building's maintenance.
In 2011, the museum board announced difficult trading conditions had forced it to review business operations at the post office and the museum.
That resulted in three redundancies, one full-time staff member and two part-time staff, all from museum operations.
Mr Clarke said it continued to be ''a very difficult business to run''.
''It's a very break-even business, if that, [but] if we got $1 for every time it was photographed ...
''We don't know what the long term holds ... they're cutting postal delivery now [but] we still run it because it's an important part of the community.''
On April 14, a day of celebrations would be held to mark the centenary, which would include activities for children and the unveiling of a commemorative plaque by former employees of the post office, including former Arrowtown mayor Jack Reid, who once worked in the telephone exchange, Marilyn Everett who retired last March after 23 years' service, and a representative from New Zealand Post.
