Ayn Rand's The Fountainhead. I had to read it senior year of high school and I spent so much time kicking up a fuss about it that my tutor eventually dropped it. It was the most boring, screedy tome I have ever read and it's not like the level of language was all that challenging, it was just all around poorly written.
Of course, I don't buy into the whole Rand conception of exceptionalism through individualism, so that might be a big part of it.
And it was boring!