He was the first king of “all the English” and the only English king to be called “the Great.” When Alfred died at the age of 50, after a remarkable reign, he was laid to rest at Winchester’s Old Minster. Just two years later, Alfred’s son Edward began construction of a new minster next to the old one, and his father’s remains were moved to a new mausoleum there in 903. The king was only to rest there for two centuries. In 1110, his body was transported to the new Hyde Abbey, along with those of his wife and son, just outside the city walls. But this too was not to be Alfred’s final resting place. At some point after the dissolution of the monasteries by Henry VIII, the monarch’s tomb may have been ransacked and the bones moved again, this time to a simple grave at St. Bartholomew’s Parish Church, which had been built partly on the site of the destroyed abbey.

There have been periodic attempts to find Alfred’s tomb for more than 100 years: The first of these was led by a local antiquary in the nineteenth century, and the second during an excavation commissioned by the Winchester City Council more than a decade ago. No tombs, and only one human bone, which turned out to be from a female, were found during either effort. And there are those who believe the king’s bones were never reburied, but rather scattered by eighteenth-century construction work on the site of the abbey. There is an increased fascination with the remains of English monarchs after the recent identification of Richard III, so last March the diocese of St. Bartholomew commissioned three archaeologists to excavate an unmarked grave in the churchyard, thought perhaps to be the location of Alfred’s last burial, in order to protect the remains from possible vandalism or theft. For now the exhumed bones lie in a secure location, awaiting further study—and the final resting place of England’s first and greatest king remains uncertain.

Though her moment in time was short, Boudicca is a towering figure of British history. As the leader of a large popular uprising in A.D. 60, she has been lauded for her defense of Britain from excessive taxation, property loss, and enslavement under the Roman Empire. And the ancient Roman historian Cassius Dio’s description of the Celtic queen has captured imaginations for millennia:

In stature she was very tall, in appearance most terrifying, in the glance of her eye most fierce, and her voice was harsh; a great mass of the tawniest hair fell to her hips, around her neck was a large golden necklace and she wore a tunic of many colors.

It is thought that, fearing capture and torture, Boudicca fled home to her kingdom in southern Britain after the final battle, during which her forces were massacred. Although Dio describes a lavish burial, the locations of neither her death nor the battle are known.

Fantastic and unsubstantiated rumors profess that the queen is buried under platform 8, 9, or 10 at London’s King’s Cross railway station, yet no traces of her have been found in this or any other location. According to Mike Heyworth, director of the Council for British Archaeology, even if remains are found that might be Boudicca’s, it would be challenging to be certain because of the lack of physical evidence that would prove it conclusively. Further, says archaeologist Richard Hingley of Durham University, if the queen died in battle, the remains would probably have been cleared away along with weapons and debris, leaving little left to find. “It is unlikely that Boudicca would have had a burial monument,” says Hingley. “Most Iron Age people in this region were disposed of in ways that do not show up in the archaeological record.” However, he adds, that has not stopped “a variety of people actively looking for the site.”

By the time he died in 1227, Genghis Khan had gone from being cast out of a minor Mongol tribe to ruling the largest contiguous empire in history, stretching from China to the Caspian Sea. Today, Genghis Khan is still worshipped as a national hero of Mongolia, but the location of his burial is shrouded in mystery. Chinese and Persian historical sources suggest Genghis died during a campaign in China, possibly falling off his horse during a hunt, and that his sons took his body back to Mongolia for burial. A number of accounts agree that his coffin was placed in a pit and that the ground above was restored to its original appearance to conceal it. According to one source, 10,000 horsemen trampled the ground above it to make it even. Beginning in the 1960s, several expeditions have searched for the grave, but without success. Today, many scholars agree that Genghis was likely interred somewhere in the Khentii mountain range of northeastern Mongolia, not far from his birthplace.

Now an international effort of the Mongolian Academy of Sciences, the University of California, San Diego, (UCSD) and the National Geographic Society is using remote-sensing techniques to search for the tomb. The team hopes finding it will close a gap in the historical record for Mongolians and the world at large. “He transformed the planet,” says UCSD engineer Albert Lin, who helped start the project in 2009. “But there isn’t even a painting of him by his own people. There’s a missing physical element to his legacy, and just finding the location of his burial would give Mongolians an important link to him.” The Mongolian government could announce the team’s preliminary findings later this year.