A collection of signatures from the country's Founding Fathers is heading to the auction block.
The 56 signatures are from a collection that had been housed in a Philadelphia building being torn down to make way for a new museum focusing on the American Revolution.
The documents were on display Tuesday in the city's Old City neighborhood at the site of the future Museum of the American Revolution in a private event for scholars, historians and students from the nearby Mastery Charter School’s Lenfest campus.
The complete set of all 56 men who signed the Declaration of Independence is expected to fetch more than $1 million at a Dec. 15 auction.
Philanthropist and media mogul H.F. ‘‘Gerry’’ Lenfest is a supporter of the charter school and board chair and benefactor of the Revolution museum, which is slated to open in late 2015.
New Hampshire-based auction house RR Auction calls it the ultimate accomplishment in American autograph collecting, with only 40 complete collections of Declaration signers known in existence.
Most of the signatures in the collection for sale are part of historically significant letters written by the Founding Fathers, not cut-out signatures or signatures on routine documents that are part of some Declaration signer collections, the auction house said.
‘‘In 32 years of business, this is the first we've come across,’’ Bobby Livingston, vice president at RR Auction, said Monday.
The highlight is a letter autographed by Georgia signer Button Gwinnett, who died in 1777 in a duel. Only 51 examples of his handwriting are believed to survive today, Livingston said.
‘‘It’s the holy grail, the ultimate prize for all collectors,’’ he said.
Other notables in the collection are a 1780 letter from John Adams that includes the oft-repeated description of America as ‘‘the city, set upon a hill,’’ as well as a 1785 letter by Benjamin Franklin bidding farewell to a friend as he prepared to leave France for his return to Philadelphia.
The collection was completed in 1905 by the noted collector Thomas Proctor of Utica, N.Y., who bound it in a red hardbound volume in a way that the pages could easily be removed and replaced with better versions of signatures as he acquired them.
It was bought in the 1920s by another well-known collector, Philip Sang of Chicago. The current owner, Richard Newell of New Hampshire, purchased the collection through a private sale in 2000 for the ‘‘high six figures,’’ Livingston said.
‘‘Most of these collections, almost all, are in public institutions and libraries,’’ he said. ‘‘Only 10 complete collections are in private hands and this is the most significant of those.’’
The new museum is expected to open in 2016.