"The Worlds Most Difficult Books"

Lists like this one from the Guardian are always arbitrary - and always thought provoking:

[Emily Colette Wilkinson and Garth Risk Hallberg] started their quest to identify the toughest books out there back in 2009, looking for "books that are hard to read for their length, or their syntax and style, or their structural and generic strangeness, or their odd experimental techniques, or their abstraction."

Here is their list:

Nightwood by Djuna Barnes
A Tale of a Tub by Jonathan Swift
The Phenomenology of Spirit by GF Hegel
To the Lighthouse by Virginia Woolf
Clarissa, or, The History of a Young Lady by Samuel Richardson
Finnegans Wake by James Joyce
Being and Time by Martin Heidegger
The Faerie Queene by Edmund Spenser
The Making of Americans by Gertrude Stein, and
Women and Men by Joseph McElroy.

I've not read any of them, unless perhaps I slogged through Swift, Woolf, Spenser and Joyce back in college, but that was decades ago. 

In recent years the most difficult-to-read book I've finished was by Jose Saramago (see Jose Saramago - King of the Comma Splice?); as I note in that post, Gabriel Garcia Marquez can be difficult to read when a sentence is 50 pages long, but in his case the content and style reward the reader sufficiently to justify the effort.

Feel free to add comments re difficult-to-read books that are nevertheless worthwhile.