Langdon knew the medieval structure well. / It was unique in the world. / Unfortunately, it was also located four thousand miles from Massachusetts.
-- Narrator (Chapter 1)

Importance: It was when Langdon saw the Florence skyline that he realized that not only he was not in Massachusetts, he was not even in the United States.

Dr. Brooks spoke steadily but quickly. ‘A bullet grazed the top of your skull and most likely gave you a concussion. You’re very lucky to be alive. An inch lower, and …’ She shook her head.
-- Sienna Brooks (Chapter 20)

Importance: When Sienna first tells Langdon what happened to him, she indicates it appeared someone had shot at him, grazing his head. Later, it is learned that Langdon was never in danger and had never been injured by a bullet. Sienna’s description of what happened to Langdon was intended to manipulate him into believing that he was in some sort of danger so he would...