Codex Seraphinianus

This is an interesting book that is organized like an encyclopedia. It feels comprehensive, but the feeling you get from reading it is something just short of understanding the world portrayed within. It has mastered a balance between something bizarre and something beautiful.

It used to be very hard to get, so I was really excited when the author put out a new edition around 2013 and bought a copy for $100+. But looks like he has been making new editions every few years now. Also, it can be found on archive.org:

https://archive.org/search?query=Codex+Seraphinianus