The Rosenbach is a Philadelphia museum and library located within two 19th-century townhouses. Established as a testamentary gift in 1954. The historic houses contain the donated collections of Philip Rosenbach and his younger brother Dr. Abraham Simon Wolf Rosenbach.

Abraham Simon Wolf Rosenbach was an American collector, scholar, and dealer in rare books and manuscripts. In London, where he frequently attended the auctions at Sotheby's, he was known as "The Terror of the Auction Room." In Paris, he was called "Le Napoléon des Livres". Many others referred to him as "Dr. R.", a "Robber Baron" and "the Greatest Bookdealer in the World".