Microsoft co-founder's $1 billion art collection unveiled, includes works by Van Gogh, Monet

Auctioneers unveiled the most expensive art collection ever to go under the hammer Wednesday, which belonged to Microsoft co-founder Paul Allen and is valued at $1 billion.

Five centuries of touchstone works featuring some of the most significant creators in history are being sold next month.

The collection of more than 150 pieces includes work by Vincent Van Gogh, Claude Monet, Paul Gauguin and Jasper Johns.

"I think this is a sale that sort of exhausts superlatives," said Johanna Flaum, vice-chairman of 20th and 21st Century Art at auctioneers Christie's.

"This is... the most valuable collection ever sold at auction. It's really a once-in-a-generation type of event."

Highlights include "La montagne Sainte-Victoire" by Paul Cezanne, which is expected to fetch at least $120 million, and "Verger avec cypres" by Van Gogh, whose hammer price is estimated at over $100 million.

Allen co-founded Microsoft with Bill Gates in 1975, becoming fabulously rich as the company grew into the computing behemoth it is today.

By the time he died in 2018 at the age of 65, he had bought some of the most important works created in the last half a millennium.

"The collection is quite wide-ranging, it really makes Paul Allen a unique collector in that sense," said Flaum.