Portraits of Princess Diana (left) Princess of Wales and Charles, Prince of Wales, painted by Andy Warhol to celebrate their wedding — have been put up for sale for $3,114,320. The paintings have not been seen since 1982, the year after the wedding, when they were completed and bought by a private collector. Warhol, who died in 1987 due to complications following an operation, is regarded as one of the 20th century’s greatest artists.