JSWolf has mentioned Ulysses
by James Joyce. So I'll rise to the bait and use my last nomination to suggest that novel.
By any standards Ulysses
is one of the most intellectually challenging books of the twentieth century, Joyce claimed that it would keep critics busy for a hundred years--and it would seem that he may well be proven right.
The book covers one day in Dublin centering primarily on Leopold Bloom. But the entire structure and events mirror Homer's Odyssey
. In some ways it is an epic of the ordinary but is far fron ordinary in its subtle structure, its phenomenally virtuosic use of language, and brilliant characterization.
The 1922 first edition has long been available in the Public domain and is included in Project Gutenberg's library, but since January of this year, nearly all editions are now PD. If you really want a challenge you won't be disappointed with this astounding novel.