The book no one can read

A 15th-century illustrated codex written in an unknown script, 'Voynichese,' has defeated cryptographers, linguists and now AI models since its rediscovery by book dealer Wilfrid Voynich in 1912. It's been held at Yale's Beinecke Library since 1969, and despite a century of attempts, no decipherment has ever been verified.

— Unknown scribe; manuscript held by Yale's Beinecke Rare Book & Manuscript Library, Voynich manuscript — Vellum carbon-dated 1404–1438