From Neolithic tablets containing the oldest known system of writing, to a series of letters scrawled on the back of a dead man’s book, some of the most legendary undeciphered codes and texts remain a challenge for even the world’s best cryptographers, code breakers, and linguists. Yet unravelling these mysterious puzzles remains as important as ever, since many of these enigmatic inscriptions could hold the keys to understanding civilizations that have long since faded into the pages of history. Here we feature ten of the most fascinating undeciphered codes and inscriptions throughout history.

In the grounds of Shugborough Hall in Staffordshire, England, sits an 18th-Century monument known as the Shepherd’s Monument, which was commissioned by Thomas Anson, a member of the British Parliament, and crafted sometime between 1748 and 1763 by Flemish sculptor Peter Schee. The Monument contains a relief, depicting a copy of a Nicolas Poussin painting ‘The Shepherds of Arcadia’, and a cipher text that has stumped historians and decoders for hundreds of years. The mysterious inscription that has yet to be decoded is located beneath the relief, and contains the letters O U O S V A V V. Framing these eight letters, at a slightly lower level, are the letters D M. So cryptic is the cipher text, that it became a feature in the international bestseller ‘The Holy Blood and the Holy Grail’ by Michael Baigent, Richard Leigh, and Henry Lincoln, and Dan Brown’s historical thriller, ‘The Da Vinci Code’. Both books presented the theory that Nicolas Poussin was a member of the secretive Priory of Sion, a Medieval monastic order, and that his painting ‘The Shepherds of Arcadia’ contains deep esoteric messages hidden within it. It is not clear whether the inscription will ever be decoded, nor whether it was ever intended to be. Whoever inscribed it must have known that the letters would last throughout the centuries, and be viewed by civilizations to come. It is possible that only a select few ever knew the purpose of the letters and what they stand for.

For hundreds of years, linguists have been trying to decode the ancient hieroglyphic script of the Maya, left behind on monument carvings, painted pottery, and drawn in handmade bark-paper books. Thankfully, decipherment has been advancing at a rapid rate and significant progress is being made. This will be a huge step forward for deepening our understanding of the social, political, and historical aspects of Maya civilization. For a long time many scholars believed that the script did not represent a language at all, or that it wasn't a complete writing system, and it is easy to see why this belief prevailed - the writing is arguably one of the most visually striking writing systems of the world. It is very complex, with hundreds of unique signs or glyphs in the form of humans, animals, supernatural objects, and abstract designs. The first major breakthrough in decipherment came during the 1950s when a Russian ethnologist proposed that the Mayan script was at least partly phonetic. His ideas were not welcomed, but he was eventually proved correct. Progress accelerated during the 1970s and 1980s when more linguistics began to take an interest in the script, and scholars came to understand that it was in fact a fully functioning writing system in which it was possible to express unambiguously any sentence of the spoken language. Despite the progress, much has remained to be decoded from the immense body of carvings and inscriptions that has languished for centuries in jungle ruins and museum closets.

During the 19th Century, ancient artifacts containing a set of etched symbols were discovered on the world-renowned Easter Island, a small remote island located a few thousand miles west of South America, and famous for the hundreds of giant monolithic anthropomorphic statues called moai. The intricate designs appear to be glyphs, or a form of writing, but the meaning of the glyphs has never been deciphered. Some believe that decoding the mysterious writing could offer answers into what caused the collapse of the ancient Easter Island civilization.

The Rongorongo writing was first discovered by Eugène Eyraud, a lay friar of the Roman Catholic Church, who went to Easter Island as a missionary on January 2, 1864. In an account of his visit, he wrote of his discovery of twenty-six wooden tablets containing the unusual inscriptions. The irregularly shaped wooden tablets were weathered, burned, or otherwise damaged when they were found. The glyphs were also found on a chieftain's staff, a bird-man statuette, and two reimiro ornaments. The glyphs are written in-between lines that run across the tablets. The Rongorongo images are shaped like humans, animals, plants, and geometric forms.

Deciphering the glyphs has proven difficult. Assuming that Rongorongo is writing, there are three barriers that make it difficult to decipher: the limited number of texts, the lack of illustrations and other contexts with which to understand them, and poor attestation of the Old Rapanui language, which is likely to be the language reflected in the tablets. Some believe that the Rongorongo is not true writing, but proto-writing, which is a set of symbols that convey information without containing any truly linguistic content. While it remains unclear exactly what the Rongorongo is intended to convey, the discovery and inspection of the tablets remain an important key to understanding the past civilizations of Easter Island.

In 1961, archaeologist Nicolae Vlassa discovered what may be direct evidence of the earliest forms of writing in the world. While conducting an archaeological excavation at a Neolithic site in Romania, Vlassa’s team uncovered three small clay tablets containing indecipherable etchings, now known as the Tartaria Tablets, which were dated to 5,500 BC.

There have been varying interpretations of the meanings of the etchings on the tablets. Some believe the etchings are an early form of writing, while others believe they are pictograms, random scribbles, religious symbols, or symbols of ownership. Due to speculation that the tablets were found at a sacrificial burial site, many believe that the symbols were of a religious context.

Overall, analysis of the Tartaria Tablets has led to many interesting hypotheses about early human culture, and the emergence of communication by writing. While ancient artifacts may initially appear to answer many questions about human civilization, in this instance, it is clear that some finds ultimately lead us to more questions than answers.

In 1908, an Italian archaeologist ventured into the ruins of Phaistos, an ancient Minoan palace on the south coast of Crete. In an underground temple depository, among burnt bones, dust, and ashes, he found a remarkably intact golden-hued disc. The discovery is known as one of the most famous mysteries in archaeology: The Phaistos Disc.

The Phaistos Disc is a large, fired clay plate, about 15 cm in diameter and 1 cm thick. Both sides of the disc are covered with a spiral of strange stamped symbols, circling clockwise towards the disc’s centre. The symbols are pictograms, portraying images including a man walking, a tattooed head, a helmet, an arrow, manacles, cats, eagles, and more. Both Sir Arthur Evans, discoverer of the Minoan capital Knossos in 1900, and Luigi Pernier attempted to translate the discs but were unsuccessful. Since that time no fewer than 26 notable attempts have been made to decipher the code. It is presumed that the writing is Linear A, a script unconnected to any known language, but some scholars suggest it is syllabic writing related to various languages, such as Hittite, Homeric Greek, Indo-European or a Semitic language. Until the Phaistos code can be cracked and the truth revealed, the golden disc will continue to draw curious linguists, analytical cryptographers, and lovers of a good ancient mystery.

In 1912, a Polish-American book dealer named Wilfrid M. Voynich went to Rome on an acquisitions trip. There he happened upon a trunk that contained a rare 15 th century manuscript now known as the Voynich manuscript. Since its appearance, this document—which is now under lock and key at the Beinecke Rare Book and Manuscript library at Yale—has been studied extensively and has stumped even the most successful cryptographers and code breakers.

The author is unidentified, as is the obscure language used throughout the text. Even many of the illustrations remain enigmatic. Very little can be made of the cryptic language used throughout the text. Some words only appear in certain sections, some letters only in certain places in words. The repetition of wording is also peculiar, and does not follow any identifiable rhythm. Many experts believe this was a language constructed by the author to hide secret information, though it does not follow any known code, causing some to speculate that the book is nothing more than an elaborate hoax. Researchers continue to investigate the enigmatic text in the hope of finally revealing its secrets.

The Dispilio tablet was discovered by a professor of prehistoric archaeology, George Xourmouziadis, in 1993 in a Neolithic lake settlement in Northern Greece near the city of Kastoria. A group of people used to occupy the settlement 7,000 to 8,000 years ago. The Dispilio tablet was one of many artifacts that were found in the area, however the importance of the tablet lies in the fact that it has an unknown written text on it. The wooden tablet was dated using the C12 method to have been made in 5260 BC, making it significantly older than the writing system used by the Sumerians. The text on the tablet includes a type of engraved writing which probably consists of a form of writing that pre-existed Linear B writing used by the Mycenaean Greeks.

As well as the tablet, many other ceramic pieces were found that also have the same type of writing on them. Professor Xourmouziadis has suggested that this type of writing, which has not yet been deciphered, could be a form of communication including symbols representing the counting of possessions. Decoding the writing is going to be difficult if not impossible, unless a new ‘Rosetta stone’ is found.

The discovery of an unidentified text in Hungary has led to more than 200 years of attempts to determine who authored it and to decipher its contents. Many scholars have studied the text, known as the Rohonc Codex, in an effort to understand its meaning and to determine who wrote it and when it was drafted. However, these efforts have been futile to date, as the meaning and origin of the text still remain a mystery.

The Rohonc Codex was discovered in Hungary in the 1800s. It is believed to have been part of the personal library of Count Gusztáv Batthyány, before he donated his entire personal library to the Hungarian Academy of Sciences. When the Codex surfaced, it initially appeared to be from medieval times. However, the text, which appears to resemble Old Hungarian script, was completely indecipherable. The mysterious text led many to wonder what the writings meant, who wrote it, and what purpose it served. Many of these questions remain to be answered, as the author has not been identified, and the text has yet to be translated.

On December 1, 1948, authorities were called to Somerton beach in Adelaide, South Australia. A dead body had been found. Little did police realize they were about to encounter what is now considered one of Australia’s most profound mysteries, with connections to the ancient world.

They found his cold body on the sand, slumped at the base of a seawall. Despite the hot weather, he wore a knit pullover and suit-jacket. His corpse revealed no obvious cause of death. Nobody knew who he was, or where he had come from. Investigators were perplexed when they found what appeared to be a secret message stuffed in his trouser pocket. The words Tamam Shud were printed on a rolled-up scrap of paper, found deep in the unidentified man's pocket. Consulting library experts, police found that the mysterious scrap had been torn from the last page of a rare copy of The Rubaiyat of Omar Khayyam.

As the investigation continued in 1949, a copy of The Rubaiyat was recovered bearing the tear-marks that matched the scrap found on the body. This very rare, first-edition book of ancient poems had been placed in the backseat of an unlocked car which had been parked along a jetty a week or two before the body had been found. The car owner turned the book in to police, but requested to remain anonymous, adding to the mysterious nature of the case. Under close inspection, the rare copy revealed scrawled letters on the back cover, grouped together in no recognizable language. Detectives determined it was a secret code, and due to the tense times of the Cold War, speculated that Somerton Man was a Soviet spy murdered by unknown enemies. No governments or intelligence agencies have ever admitted knowing the man. The Rubaiyat code was made public and many tried to decipher it in vain, but it remains uncracked to this day.

The Danube Valley civilization is one of the oldest civilizations known in Europe. It existed from between 5,500 and 3,500 BC in the Balkans and covered a vast area, in what is now Northern Greece to Slovakia (South to North), and Croatia to Romania (West to East). During the height of the Danube Valley civilization.

One of the more intriguing and hotly debated aspects of the Danube Valley civilization is their supposed written language. While some archaeologists have maintained that the ‘writing’ is actually just a series of geometric figures and symbols, others have maintained that it has the features of a true writing system. Harald Haarmann, German linguistic and cultural scientist and leading specialist in ancient scripts and ancient languages, supports the view that the Danube script is the oldest writing in the world. The tablets that were found are dated to 5,500 BC, and the glyphs on the tablets, according to Haarmann, are a form of language yet to be deciphered. The symbols, which are also called Vinca symbols, have been found in multiple archaeological sites throughout the Danube Valley areas, inscribed on pottery, figurines, spindles and other clay artifacts.

However, the majority of Mesopotamian scholars reject Haarmann’s proposal, suggesting that the symbols on the tablets are just decoration. This is despite the fact that there are approximately 700 different characters, around the same number of symbols used in Egyptian hieroglyphs.

By April Holloway