The 3rd book by Dan Brown that features character Robert Langdon is set in what city?
Robert Langdon: Professor Robert Langdon is a fictional character created by author Dan Brown for his "Robert Langdon" book series: "Angels & Demons" (2000), "The Da Vinci Code" (2003), "The Lost Symbol" (2009), and "Inferno" (2013). The Lost Symbol:  It is a thriller set in Washington, D.C., after the events of "The Da Vinci Code", and relies on Freemasonry for both its recurring theme and its major characters.
Washington, D.C.