A three-metre slab covered in an unknown script stood at the mouth of the Singapore River for centuries. In 1843 an engineer blew it up to widen the harbour. One fragment survives, and the writing has never been deciphered.

A civilization of a million people left behind planned cities, covered drains, standard weights and about four thousand tiny inscriptions. After a century of work nobody can read one, and some scholars argue it was never writing at all.

A Hungarian count gave away his library in 1838. Inside it sat a small, fat book written in a script that matches no alphabet on earth. Nearly two centuries and a dozen rival decipherments later, not one sentence of it has been read in a way other scholars accept.

A serial killer taunted San Francisco with encrypted letters. Two of his four ciphers have been cracked — one took 51 years — yet his identity remains a blank.

A 15th-century codex filled with impossible plants, bathing women and a script no one has ever decoded has defeated medieval scholars, WWII codebreakers and modern artificial intelligence alike.

For 35 years, 97 letters on a copper sculpture at CIA headquarters have defeated the world's best codebreakers. In November 2025 the answer was sold for $962,500 — to an anonymous buyer sworn to keep it secret. The mystery was sold. It was not solved.

In 1908, a clay disc stamped with 241 mysterious signs emerged from a Minoan palace on Crete. It may be the world's first printed text — and no one can read it.

Easter Island's wooden tablets carry one of the last undeciphered scripts on Earth — and a 2024 dating study hints it may have been invented with no outside help at all.

An 1885 pamphlet claimed a fortune in gold lies buried in Virginia, its location locked in unsolved ciphers. Skeptics say the treasure never existed - yet people are still digging.

In 1897, Edward Elgar slipped a young friend a card covered in 87 curling symbols. She never managed to read it, no one has since — and the man who wrote it took the answer to his grave.

In January 2012 an anonymous image on 4chan promised to find "highly intelligent individuals." Three global puzzle hunts later, a runic book remains unread — and nobody knows who was asking.

For over 250 years, a short row of letters carved on an English garden monument has defied every attempt at decipherment - reportedly including Darwin and Dickens, and certainly the codebreakers of Bletchley Park. Eight letters may be too few ever to prove any answer right.