Some books written in English are meant to be a tough nut to crack. They can be constructed as an intricate experiment, contain countless made-up words and obscure references, have more characters than you can keep track of, and generally intimidate an unprepared reader with how enigmatic, seemingly impenetrable and weird they are. It might be especially tough if English isn't your first language. However, getting through them, even if takes a lot of time and effort, can be deeply enlightening and rewarding.

Here are 5 most challenging fiction books written in English that never fail to fascinate, puzzle and confuse readers all over the world:

Gravity’s Rainbow by Thomas Pynchon

What it's about: written in 1973 by American writer Thomas Pynchon, this novel is set at the end of World War II and focuses on the secret development and deployment by the Nazis of a mysterious rocket and the search for it undertaken by several characters.

What makes it difficult: this unconventional postmodern 760‐page long book is a mix of different styles and seemingly has everything - from philosophy and poetry to math equations and pop culture references as well as more than 400 characters. It even uses quantum mechanics as a literary metaphor!

Moby-Dick; or, The Whale by Herman Melville

What it's about: an 1851 novel by American writer Herman Melville is written from the point of view of a sailor named Ishmael who tells a story of the obsessive quest of Ahab, captain of the whaling ship Pequod, for vengeance against Moby Dick, the giant white sperm whale that bit off his leg on the ship's previous voyage.

What makes it difficult: this is another complex literary experiment that mixes different genres and includes numerous philosophical tangents, allusions to literature, mythology, historical events, and, of course, plenty of encyclopedic descriptions of whales.

The Sound and the Fury by William Faulkner

What it's about: the novel written by the American author William Faulkner (it came out in 1929) is set in Jefferson, Mississippi, in the first third of the 20th century. It tells a tragic tale of the dissolution and ruin of the Compson family over several decades.

What makes it difficult: the novel is written from several perspectives, including the one of a cognitively disabled 33-year-old man. The narrative itself is non-chronological and includes a stream of consciousness - the written equivalent of the character's thought processes with little punctuation, and sentences starting and stopping abruptly.

Ulysses by James Joyce

What it's about: the events of the novel by Irish writer James Joyce, first published in 1922, take place in and immediately around Dublin on a single day (June 16, 1904). It focuses on three central characters—Stephen Dedalus (Joyce's literary alter ego), Leopold Bloom, a Jewish advertising canvasser, and his wife, Molly.

What makes it difficult: often described as an encyclopedic novel, Ulysses contains chapters written in different tones and styles, more than 30,000 distinct words, including several invented by Joyce, as well as numerous literary puzzles and experiments, mysterious allusions, unique idioms and hundreds of words of interior monologue.

Finnegans Wake by James Joyce

What it's about: there's no definitive plot synopsis.

What makes it difficult: the novel, which took Joyce 17 years to write, has no real beginning or end (it ends in the middle of a sentence and begins in the middle of the same sentence). By combining words from different languages, experimenting with them and inventing new ones, Joyce managed to create a unique language that seems practically illegible to some readers. It took one book club 28 years to finish the novel!

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