Give me a list of books that are long and hard to read. The sort of books with which I could impress someone who read a lot.
When talking to someone well read, I would go with some of the classics of literature. The following books require a very detailed read in order to be able to understand them, due to the complex topics they analyze. They are long, but also considered masterpieces:

- "Crime and Punishment" by Dostoievsky
- "Ulysses" by James Joyce
- "The Magic Mountain" by Thomas Mann
- "Gravity's Rainbow" by Thomas Pynchon
- "Don Quixote" by Miguel de Cervantes
- "Infinite Jest" by David Foster Wallace