Several scenes in It. The Library scene was a big one. I always saw my hometown library when I read that. But several others as well.
The Library Policeman: when he pushed his boxcutter up to the protagonist's neck. I had to stop reading, it was about 2:00 am, and go around making sure all my doors and windows were locked. Then I had to turn on the tv and watch a couple Andy Griffith episodes before I could get to sleep. I've often thought this story was an overlooked masterpiece.
And Gramma. I kept seeing my own Grandma when she was ill at the end and we were at her house taking care of her. She was a sweetheart but that's the image that kept rising to my mind. Very scary.