Codex Seraphinianus, 1976-1978
‘The Codex Seraphinianus is a book written and illustrated by Italian artist, architect and industrial designer Luigi Serafini, from 1976 to 1978. The book appears to be a visual encyclopedia of an unknown world, written in one of its languages, an alphabetic writing intended to be meaningless.’
I skimmed through that once in a library… I really need to get my own copy.