Curators say the Maison Mantin in Moulins, central France offers a unique freeze-frame of turn-of-the-century France in all its grandeur and strangeness.

What precisely lay behind the imposing 19th century mansion's locked doors and shuttered windows had been the subject of intrigue for decades.

Some believed that its wealthy, unconventional former owner, Louis Martin, had hidden a collection of human skeletons among its many rooms.

It was closed shortly after his death in 1905 and its contents left to attract dust, mold, woodworm and rats.

Mr Mantin made his fortune in land and property but died unmarried and childless aged just 54 – only eight years after the sumptuous home was completed. It had been built on the ruins of a 15th-century castle that had belonged to the aristocratic Bourbon family.

In his will, he bequeathed the house to the town, specifying that he wanted it to be made a museum a century after his death.

Although he left no orders to have it sealed, the mansion was left practically untouched all those years, its eerie calm even unbroken by the occupying German forces of the Second World War.

"It was very strange, the house became a sort of urban myth," said assistant curator Maud Leyoudec. "People didn't know what was in this house and had fantasies."

time capsule