The dress Marilyn Monroe wore during her “Happy Birthday, Mr. President” performance will be going up for auction this fall.

Marilyn Monroe Dress

When Monroe sang “Happy Birthday” to President John F. Kennedy ahead of his 45th birthday, she wore a form-fitting, flesh-colored dress. The event, held at Madison Square Garden, doubled as an early birthday celebration for Kennedy and a Democratic fundraiser. More than 15,000 guests were present.

Monroe’s performance became a lasting pop culture moment. The model-turned-actress had sang a sultry version of the classic “Happy Birthday” song that started rumors that she and the president were having an affair. Also of note is the fact that First Lady Jacqueline Kennedy wasn’t present at the event.

The dress Monroe wore to sing Kennedy “Happy Birthday” was a custom Jean Louis creation that featured more than 2,500 hand-stitched crystals. Monroe, who wore nothing underneath the dress, had to be sewn into it.

Monroe’s dress was purchased in 1999 by the late fund manager Martin Zweig for $1.26 million. His estate is now offering the dress up for action, and is expecting to earn at least $2 million when it sells to the highest bidder.

“It’s like the equivalent of a Monet, just because of its historic significance and its connection to one of the most important actresses of our time,” said Darren Julien, the president and chief executive of Julien’s Auction.

Monroe’s dress will be up for auction Nov. 17 through 19.