WARSAW, Poland (AP) — Peter Paul Rubens' 17th century masterpiece “Portrait of a Lady” is set to go up for auction in Poland next month, the DESA Unicum auction house said Thursday.

The Flemish master's oil-on-canvas portrait of a dark-haired woman in a rich black velvet dress has an estimated value of 18 million to 24 million zlotys ($4.5 million- $6 million).

The painting, currently owned by a British citizen, will be auctioned off to a new buyer in Warsaw on March 17. It is expected to be one of the largest art sales ever to take place in Central or Eastern Europe, according to DESA Unicum.

“This exceptional piece of art, one of the most precious in the world, has made its way to us,” DESA President Juliusz Windorbski said during a news conference. "We are living a dream of every auction house in the world.”

Experts say the work, painted by Rubens around 1620-25, with involvement from his workshop, could be a likeness of Rubens’ first wife, Isabella Brant, or of a member of the Duarte family of jewelers, who were Rubens' neighbors.

Offered at the same auction will be works by Italian painter Giovanni Battista Lampi, who lived between 1751 and 1830, and by Polish masters of the 19th and 20th centuries, including Jacek Malczewski, Leon Wyczolkowski and Aleksander Gierymski.