A villa in the Italian capital Rome housing the only mural by Caravaggio is being auctioned on Tuesday, with a starting price of €471m (£394m).
Villa Aurora is at the centre of an inheritance dispute between its current occupier, Texas-born Princess Rita Boncompagni Ludovisi, and her stepsons.
The six-storey property is a treasure trove of art, including frescoes by artist Guercino.
Thousands have signed a petition for it to be returned to the state.
The highlight of the villa’s many treasures is the wall painting by the 16th and 17th Century artist Michelangelo Merisi, better known as Caravaggio.
The oil painting, which contains nudity, depicts the gods Jupiter, Neptune and Pluto, with the world at its centre and marked by signs of the zodiac.
It is the world’s only surviving Caravaggio mural, itself estimated to have a value of €310m (£259m). It was painted in 1597 after the villa’s first owner commissioned it for his alchemy room.
However, Villa Aurora got its name from another of the property’s artworks, a fresco painted by the Italian Baroque artist Giovanni Francesco Barbieri, known as Guercino. The painting depicts the goddess Aurora, or Dawn, on her chariot.
Art-lovers are demanding that the Italian government steps in to buy the villa so that its many treasures can be made available for public viewing. More than 38,000 people have signed a petition calling for the state to intervene.
Italian law does give the state the option to buy the property, but only after the auction has taken place, and for the same price.
But the villa has an estimated value of a quarter of the annual budget of the Italian culture ministry, so it is far from clear if the government can afford to intervene.
The legal battle over the villa’s ownership began after the death in 2018 of Prince Nicolo Ludovisi Boncompagni, who was head of the family which has owned Villa Aurora for generations.
The dispute is between his third wife, Rita Boncompagni Ludovisi, and his three sons from his first marriage.
Princess Rita says that her late husband’s will gives her the right to live in Villa Aurora for the rest of her life, and that if sold, the proceeds would be split between her and her stepsons.
However, an agreement could not be reached between the parties and a court ruled that an auction should be held. The princess says she would like the villa to be returned to the state.
Princess Rita, born in Texas as Rita Carpenter, has led an interesting life of her own. She worked as an actor and a journalist in the US, before moving into the property business. She was involved in the sale of the General Motors building in New York to Donald Trump in 1998.
But after marrying Prince Nicolo and moving to Italy, she dedicated her life to the restoration of Villa Aurora, which was in a state of disrepair when she first saw it in 2003, she says.