The historic Summer Street building now features change rooms, a mini cafe, retail space for local businesses, customer service desks, and other services including banking.

"What an amazing transformation," mayor Jason Hamling said at an opening ceremony on Monday.

"It's great to see one of the city's most significant landmarks being reinvented."

The 144-year-old Orange building was almost entirely gutted over about three months. The new "Community Hub" layout is an Australia Post trial to reinvent brick-and-mortar sites for the internet age.

"[Orange] was chosen because we were able to take back the old post office ... restore it beautifully from the outside, and transform it from the inside into a modern, exciting retail experience," Australia Post CEO Paul Graham said.

"This is about representing what the community is telling us is important to them. A broader range of services."

The renovated post office is now open to the public. Temporary sites in Orange City Centre were erected while renovations took place.

Member for Calare Andrew Gee, mayor Jason Hamling, MLCs Stephen Lawrence and Sam Farraway, Orange City Council CEO David Waddell, and Australia Post CEO Paul Graham attended the opening.

New Australia Post Community Hubs in Victoria, Tasmania, and Queensland are due to follow in 2024.

Orange Post Office was built in 1879 at a cost of about £6000. Postmaster General Saul Samuel opened the building in a ceremony on February 10, 1880.

Several major renovations were carried out during the 20th century, with the last in 1995. The exterior clock assembly was electrified in 1983.

The Summer Street building is protected via NSW's State Heritage Register and the 2011 Orange Local Environmental Plan.

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