Seventy-two-year-old Lina Renault and her brothers have won the title to the buildings, valued at about $90 million.
Renault, who came from a humble background, said she promised to sort out the inheritance at her mother's deathbed, reported the Sunday Telegraph.
The great-uncle Joseph-Paul Mauprivez, was apparently sole heir to the estate of Countess Octavie de Coetlogon, who died in 1865.
The deeds were lost in a 1910 flood, but in 1970, Renault came across a copy of a crucial deed in a Paris archive and has been in court ever since.
A Paris court is expected to make a final ruling on the building next month.
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