(CNN) -- A collection of rare ancient Greek coins which has been hidden away for two decades is expected to sell for millions of dollars when it goes up for auction in New York on Wednesday.
The Prospero Collection features coins of historical and artistic importance, including one described by an expert as "a masterpiece of ancient Greek art."
Assembled by a private collector over three decades, from 1960 to 1991, the treasure trove has remained untouched for the past 20 years.
After so long out of the spotlight, the coins have attracted serious interest from potential buyers around the world and at recent viewings in the U.S. and the UK.
Paul Hill, ancient Greek coin specialist at dealers A. H. Baldwin & Sons, the company behind the sale, said many of the coins were "miniature works of art."
The most valuable item in the collection is a gold stater featuring the head of a bearded satyr and the figure of a winged griffin, which the auction catalog describes as "without doubt the greatest ancient Greek gold coin."
Hill said the lot, "a masterpiece of ancient Greek art," had a pre-sale estimate of $650,000 and may eventually go under the hammer for as much as $1 million.
He said that while most of the lots were likely to sell to collectors, coins were increasingly being seen as an attractive investment, given the global financial crisis.
"They are of great artistic beauty and historical significance, which makes them more interesting than stocks or shares, and they are tangible and portable, compared to a big estate."
"Such passion has gone into the collection, and it has been an important part of somebody's life for so long, that there is an element of sadness to see it split up," Hill told CNN.
"But it is lovely to see it published together now, for posterity, before it is 'recycled' and finds new homes with new collectors all over the world."
The Prospero Collection will be sold at auction at the Waldorf Astoria Hotel in New York on January 4, 2012.