"had once hung" is correct and can be used in written English.
It is the past perfect tense of "hang," indicating that something was previously hung in the past. Example: The antique painting that had once hung in the hallway was now displayed prominently in the living room.
Someone even told him it had once hung in the president's office.
All that remained was a small hole in the wall where Hina's diploma had once hung.
A large carved owl had once hung outside the house, a sort of guardian.
Government Printing Office" had once hung out front, but, after President Eisenhower and his driver struggled to find the entrance, it was replaced with the C.I.A.'s emblem.
But Memuna, as she is called, had become the poster child for the amputees: her picture had once hung at the United Nations.
First I walked under the smooth horizontal arch of the jaw, and its palate, where the baleen had once hung, sheets of age-browned bone.
As he checks into a hotel near the Old City, Thubron peers through windows that overlook crossroads "where the Taliban had once hanged their victims on makeshift gallows".
Set in gold, the Tanguy (pronounced tahn-GHEE) resembles a minuscule version of a painting that might have once hung in a Venetian palazzo, which could help explain why some of his paintings can hint at Canaletto's open piazzas, wandering figures and extended shadows.
The familiar smell of book dust – the "finest pollen in the world", as he had once described it – hung heavy and familiar.
As vice chairman of the Federation of Conservative Students, the student organization of the British Conservative Party, during the 1980s Hoile had once worn a "Hang Nelson Mandela" badge.
As vice-chairman of the Federation of Conservative Students, the student organisation of the British Conservative Party, during the 1980s Hoile had once worn a "Hang Nelson Mandela" badge.
