The book was written by some college professor who's spent her entire professional life in an 'ivory tower'.
The two skyscrapers 'tower above' the other buildings of the city.
She's been a/my 'tower of strength' during my illness.
(..) When he killed Snape, he thought the wand would become his. But the thing is... The wand never belonged to Snape. It was Draco, who disarmed Dumbledore that night in the Astronomy tower. From that moment on and the wand answered him, Until, the other night when I disarmed Draco. At Malfoy Manor. (..)2011 Harry Potter and the Deathly Hallows: Part 2
(..) - No. I think it's best if you two talk alone. She's very shy. You're the Grey Lady. The ghost of Ravenclaw tower. I do not answer to that name! No, I'm sorry, I'm sorry! It's Helena, isn't it? Helena Ravenclaw, Rowena's daughter. Are you a friend of Luna's? (..)2011 Harry Potter and the Deathly Hallows: Part 2