It is the finest collection of modern art anywhere outside Europe and the US, boasting works by Jackson Pollock, Francis Bacon, Andy Warhol, Edvard Munch, René Magritte and Mark Rothko.
But the pieces have been stacked in the basement of Tehran's Museum of Contemporary Art for more than 30 years, gathering dust in storage. Censors in Iran classed some as un-Islamic, pornographic or too gay, and they have never been shown in public. Others have been displayed only once or twice.
But now a number of the collection's paintings are on show for the first time in Tehran as part of the museum's Pop Art & Op Art exhibition, featuring works by Warhol, David Hockney, Roy Lichtenstein, Victor Vasarely, Richard Hamilton and Jasper Johns.
"Many of the works in the exhibition are shown for the first time," Hasan Noferesti, the museum's director for art programmes, told the Mehr news agency. "The exhibition aims to show the evolution of these artistic movements."
More than 100 pieces from the museum's remarkable collection are on display, according to Mehr, along with a series of works from Mexico that have been dedicated to the museum in commemoration of the 100th anniversary of the Mexican revolution and the 200th anniversary of the country's independence.
James Rosenquist, Jim Dine, Larry Rivers and RB Kitaj are among other artists whose works are in the exhibition, which runs until mid-August.
Iran's unique hidden treasure was bought before the Islamic revolution, under the supervision of Farah Pahlavi, the former queen of Iran, who fled the country with the late shah Mohammad Reza Pahlavi in 1979.
The 38-year reign of the shah, self-proclaimed kings of kings, came to an end after Ayatollah Ruhollah Khomeini returned from exile to Tehran receiving a hero's welcome and founded the Islamic republic.
The collection includes Pollock's Mural on Indian Red Ground, considered to be one of his most important works and estimated to be worth more than $250m, as well as important pieces by Picasso, Van Gogh, Monet, Pissarro, Renoir, Gauguin, Toulouse-Lautrec, Degas, Whistler and Marcel Duchamp.
There are even pieces by artists whom the former empress met in person, including the Russian-French painter Marc Chagall and the English sculptor Henry Moore. The collection is thought to be worth more than $2.5bn.
