It's one of the finest collections of modern art anywhere in the world, but you won't find it in New York or Paris.
Dozens of works by the likes of Pablo Picasso, Andy Warhol and Jackson Pollock -- together valued at roughly $3 billion -- are locked in a basement in Tehran.
Only a handful of westerners have had an up-close look at the underground archives in Tehran's Museum of Contemporary Art. ABC News was granted exclusive access inside the vault that holds a priceless collection Iranian authorities choose to keep locked away.
What was revealed was astonishing: a series of paintings by Picasso; a wall's worth of pop art by Roy Lichtenstein; Warhol portraits of Jackie Onassis, Mick Jagger and Marilyn Monroe; a Diego Rivera self portrait; and a painting many consider to be the best Jackson Pollock outside of North America.
The collection was supposed to be a gift to the Iranian people. It was assembled by the Shah of Iran and his wife using public funds during the oil boom of the 1970s. Tehran's Museum of Contemporary Art was inaugurated in 1977, designed to be one of the world's landmark modern art institutions, with an international collection worthy of that ambition.
But just months later came the Islamic Revolution. The Shah was deposed, Ayatollah Khomeinei was became the country's leader, and in the Revolutionary, anti-American climate the museum's western art was banished to the basement.
Why aren't the pieces shown to the public? The reasons are a mix of ideology and practicality.
The collection is huge and the museum small. Museum director Dr. Habibollah Sadeghi, himself a painter appointed by conservative President Mahmoud Ahmedinejad, says there is no space to properly put the works on display.
Others question whether the museum could properly protect the valuable pieces from theft or damage were they displayed openly.
Conservative Muslim ideology -- a powerful governing force in Iran -- has played a similarly forceful role in keeping the pieces underground. Aside from the anti-Western overtones of Revolutionary Iran many of the pieces are considered too racy for a conservative Muslim society.
When some of the collection briefly went on display in 2005 Andre Derain's "Golden Age," a 1905 painting of female nudes, was notably absent. Also hidden was the centerpiece of a Frances Bacon painting triptych. The center panel could be taken as homoerotic, showing two naked men asleep in bed.
There are plans to display the collection permanently once museum space is expanded, Sadeghi said. If those plans materialize -- full-time public access to view the pieces -- it would fulfill the dreams of art lovers worldwide.
"In two or three years we can improve the museum and have a permanent exhibition," said Sadeghi, adding that the museum is hoping to buy more Western works in the coming years to fill out the collection.
Sadeghi, who was appointed by President Mahmoud Ahmedinejad, expressed a warm outreach in a Western culture the Iranian leadership publicly reviles.
"We hope we can buy 100 paintings from Europe and America. We really respect [their] culture and we hope they respect us too," he said.
Among the types of work they hope to add to the collection: Mexican revolutionary art, perhaps seen as consistent with the revolutionary ideals of Iran's ruling regime.
The Iranians insist the Western works are safe and well-maintained in the climate-controlled basement. It is a coveted collection -- art lovers around the world have tried to buy the pieces, but Sadeghi says they are not looking to sell.
There is only one known instance of a piece departing from the Iranian archives: a work by abstract expressionist Willem de Kooning was traded for rare illustrated pages of the Shahnameh, an Iranian epic poem.
For the time being the collection seems intact, though kept underground and well out of the public eye.