Masterpieces by Picasso, Renoir and Matisse will go on sale in London next month after being hidden from public view for longer than a generation.
The artworks go under the hammer at Christie's in its Impressionist and Modern Art Evening Sale, which is expected to raise nearly £70 million.
In the meantime, the public are being offered the chance to catch a glimpse of the artworks at an exhibition. The sale includes 48 works by leading artists and has been given a total value of £69,110,000.
Artwork going on view ahead of the sale includes Tete de femme (Jacqueline), 1963, by Pablo Picasso, a portrait of the artist's second wife. Christie's said the painting has been unseen in public since 1967 and is expected to fetch £3 million to £4 million.
The portrait has never been offered at auction before and has remained in the same collection since 1981. Jacqueline was said to have had a short neck and the artist would often "humorously" exaggerate its size in portraits. Mademoiselle Grimprel au ruban rouge, 1880, is said to date from the high point of Pierre-Auguste Renoir's portrait painting. It is being shown in public for the first time since the 1960s and is expected to realise £1.8 million to £2.5 million.
Other important pieces in the sale include Espagnole, circa 1916, by Natalia Goncharova, described by the auction house as "one of the finest examples of the artist's work to be offered at auction". It is being publicly exhibited for the first time since 1971 and is set to realise £4 million to £6 million.
Gitane, circa 1910 to 1911, by Kees van Dongen is described as a "striking" portrait by the Dutch artist, executed at one of the most important periods of his career. It carries an estimate of £5.5 million to £7.5 million.
Meanwhile, Nu aux jambes croisees, 1936, by Henri Matisse, can be seen by the public for the first time since 1951 and is estimated to reach £2.5 million to £4 million.
The full exhibition for the Impressionist and Modern Art Evening Sale takes place from next Wednesday to February 2 at Christie's. The auction will be held on February 2 at 7 p.m.