I just finished reading Neal Stephenson’s Anathem. Very interesting, very complex, and very long (the story concludes on page 890).
It took a good 100 pages to really feel immersed in the world of the book, which involves a good bit of made up terms (the book includes a 20 page glossary).
I hesitate to recommend it because of its length. It would have been good to have a large block of time to read it, rather than spreading it out over 3 ½ weeks, so perhaps if you’re going on a reading vacation. Or flying from California to the UK.
If you do read it, stick with it until you feel yourself really getting absorbed into the world of the book, then go back and start from the beginning again.