The Lost Symbol, formerly known under the working title as The Solomon Key, is the third book to feature Harvard University symbologist Robert Langdon. The book takes place in Washington, D.C. and focuses on Freemasonry and The Lost Symbol, a reference to a ciphered pictogram in an important talisman, the Hebrew Key of Solomon. Originally expected in 2006, this book has been pushed back multiple times. It was first released in September 2009 with an initial print run between 5 to 6.5 million copies, it was at the time the largest first printing in Random House's history.