Twelve works from the Blaquier-Arrieta collection are due to be auctioned in New York overnight from Wednesday to Thursday, with Sotheby’s estimating they could fetch up to $450 million (€402 million) in total.

The sale includes Châtaigniers en fleurs by Vincent van Gogh and L’Arlequin by Paul Cézanne, two of the collection’s most valuable paintings.

Argentines Carlos Pedro Blaquier and Nelly Arrieta de Blaquier began collecting art in the 1960s. In the following decade, with the help of galleries including Lefevre and Wildenstein in London, they acquired major Impressionist and Post-Impressionist works.

Simon Shaw, Sotheby’s specialist in Impressionist and modern art, said the collection “does not look at all like a private collection,” but more like “a small museum, a miniature Musée d’Orsay.”

Many of the works have never been loaned to museums or shown to the wider public. As a result, the collection has gained “an almost mythical status in the art world,” according to Philip Hook, former head of Sotheby’s Impressionist and modern art department in London.

That is especially true of the Van Gogh and Cézanne paintings, bought by the couple in 1975 and kept from public view ever since. Sotheby’s said those two works alone could sell for as much as $300 million (€266 million).

The auction will also feature paintings by Camille Pissarro, Pierre-Auguste Renoir, Edgar Degas, Claude Monet, Paul Gauguin, André Derain, Maurice de Vlaminck, Alfred Sisley and Henri de Toulouse-Lautrec.