Literary Treasure Hunt: Clue #3

Here's the third clue to the "hidden" copies of Thrones located in historic spots around DC.  To find this book, solve this clue, be the first to visit the site and claim your prize.  Good luck!

Clue #3

A DC institution, this grand historic hotel has hosted almost every U.S. president since Franklin Pierce in 1853. Other notable guests have included Charles Dickens, Buffalo Bill, and P.T. Barnum. On August 28, 1963, the Reverend Martin Luther King wrote his famous "I have A Dream" speech while a guest here and Mark Twain penned two books here in the early 1900s. The concierge holds the prize at this location.