JEWEL SAMAD via Getty Images A copy of the Emancipation Proclamation and the 13th Amendment will soon be auctioned.

Two of the most important documents of American history could soon be yours, if you have millions to spend.

Rare copies of the 13th Amendment, which abolished slavery, and the Emancipation Proclamation will be sold by Sotheby's, an auction house in New York, during its “Two Centuries of American History” auction on May 25. It is the first time both copies of the anti-slavery documents will be up for sale, simultaneously.

"The significance of them is really overwhelming," Selby Kiffer, international senior specialist for books and manuscripts at Sotheby's, told the Huffington Post. "In terms of historical significance -- other than the Declaration of Independence, bill of rights and the constitution -- these rare two documents are some of the greatest documents of American history."

The 13th Amendment, signed by President Abraham Lincoln, is only one of 14 original copies that exist, most of which live within the confines of various museums and institutions, Kiffer said to HuffPost. Lincoln, who signed the document on February 1, 1865, called the amendment a "king's cure for all the evils." A copy was consigned by The Gilder Lehrman Institute of American history, a non-profit dedicated to the development and preservation of history education, which is selling the document to raise money for the resources it needs.

The copy of the Emancipation Proclamation up for auction -- which was dated January 1, 1863, and freed all slaves in confederate-owned territory -- is one of 27 copies in existence, 20 of which are framed in institutions. The remaining copies are owned by private collectors, one of whom, Kiffer said, bought a copy of the document from Sotheby's in 1989 and is now putting it back up for auction.

The anti-slavery documents will be on sale to the public and are expected to attract millions of dollars. The Emancipation Proclamation is estimated to fetch between $1.5 to $2 million while the 13th Amendment is estimated to sell between $2 to $3 million.

CORRECTION: The copy of the Emancipation Proclamation up for auction was dated January 1, 1863, not January 1, 1983.