1. Genghis Khan

The Mongol leader conquered more territory than any person in history, yet very little is known about what he looked like, how he died or even where he is buried. Legend has it that upon his death in 1227, the Great Khan’s soldiers honored his request to keep his gravesite a secret by butchering anyone who saw his funeral procession. They then ensured their own silence by killing themselves. Another account has the men concealing the grave by trampling it with 10,000 horses, and still another claims they diverted a river over it to protect it from robbery and desecration. Genghis Khan’s final resting place has since become one of the most sought after prizes in archaeology. Researchers suspect it may be located in Mongolia’s Khentii Province, but despite looking for it with everything from ground penetrating radar to satellite images, no team has yet to strike pay dirt.

2. Wolfgang Amadeus Mozart

wolfgang amadeus mozart
Sean Gallup / Getty Images
A portrait of Mozart shortly before his death.

When the wunderkind composer died from a mysterious illness in 1791, his body was placed in a wooden coffin and interred in an unmarked common grave in Vienna’s St. Marx cemetery. There it lay for several years until the early 19th century, when—in accordance with the practices of the time—it was dug up and most likely dispersed or crushed to make room for new burials. Its location in the cemetery has since been lost. A potential piece of Mozart’s body later resurfaced courtesy of a St. Marx gravedigger, who claimed he recovered the composer’s skull in 1801 after marking it with metal wire when it was first buried. The skull was given to Salzburg’s International Mozarteum Foundation in 1902, but DNA analyses have thus far been unable to prove whether it actually belonged to Mozart.

3. Cleopatra

Shortly after Augustus and his Roman legions invaded Egypt in 30 B.C., the enigmatic Queen of the Nile is said to have taken her own life by poisoning—possibly with a bite from an asp. Her suicide closely followed that of her paramour, Mark Antony, and the ancient chronicler Plutarch writes that the two star crossed lovers were then laid to rest “in splendid and regal fashion” in a tomb near Alexandria. The story trails off from there, however, leaving archeologists with a Sphinx-sized riddle. Some believe the mausoleum ended up at the bottom of the sea after fourth and eighth century earthquakes changed the topography of Alexandria, while others claim the couple may be buried near Taposiris Magna, an ancient temple that has yielded dozens of tombs and mummies.

4. Thomas Paine

thomas paine
DeAgostini / Getty Images
Thomas Paine.

During the heady days of the 1770s, writer and pamphleteer Thomas Paine helped sound the call to arms for the American Revolution in such works as “Common Sense” and “The American Crisis.” Though once considered a hero, he was later denounced for attacking the church in his book “The Age of Reason,” and only a handful of people attended his burial when died in 1809. The indignities only mounted a decade later, when a man named William Cobbett exhumed Paine’s corpse and shipped it to his native England, where it was believed it would be honored with a memorial. Cobbett was unable to drum up interest in a Paine monument, however, and the remains supposedly spent the next several years gathering dust in his attic. Some accounts say the great thinker’s bones were later thrown in the garbage or even recycled into buttons, but they may have also been auctioned off piecemeal. Since the 19th century, different collectors have claimed to possess Paine’s skull, his hand and his jawbone.

5. Attila the Hun

attila the hun
Palais Bourbon / Wikimedia Commons
Attila the Hun.

The Hunnic raider known as the “Scourge of God” suffered a famously anticlimactic death in 453 A.D., when he supposedly passed out drunk on his wedding night—one of many that he enjoyed—and choked from a nosebleed. Attila’s warriors honored their barbarian chief with a day of grief and funeral games before burying him in a trio of coffins—one of gold, one of silver and one of iron. As in the case of Genghis Khan, the ceremony was conducted in secret, and the unfortunate prisoners who dug the plot were killed to deter grave robbery. Whether the safety measures actually worked is a matter of debate. While the grave is widely believed to be located somewhere in Hungary, no trace of Attila or his priceless triple coffin has ever been found, suggesting the site may have been looted in the years after his death.

6. Sir Francis Drake

Queen Elizabeth I’s favorite privateer met his end in Panama in 1596, having spent the previous two decades harassing Spanish holdings in the New World and undertaking a circumnavigation of the globe. After his death, Drake was dressed in his armor, sealed inside a lead coffin and given a traditional burial at sea some 14 miles off the coast of Portobelo. His remains have since been lost in the Caribbean, but that hasn’t stopped scores of divers, archaeologists and treasure hunters from seeking them out. A rare breakthrough came in 2011, when a mission financed by American entrepreneur Pat Croce found what is believed to be the wreck of two of Drake’s scuttled ships. The team also searched in vain for the navigator’s coffin, but the precise location of his 400-year-old watery grave remains a mystery.

7. Alexander the Great

Alexander the Great
DEA / G Nimattallah / De Agostini / Getty Images
Alexander the Great.

Alexander died in Babylon in 323 B.C., having led his Macedonian armies on a decade-long campaign of conquest from Greece to India. In keeping with his famously immodest moniker, the deceased warrior-king was placed in a gold sarcophagus and coffin and eventually taken to a tomb in Alexandria. His body was moved to a mausoleum a few years later, where it became something of an ancient tourist attraction. Julius Caesar and Augustus both paid their respects, and Caligula supposedly looted Alexander’s armored breastplate during a visit in the 1st century A.D. The Roman Emperor Septimus Severus finally had the tomb sealed off for good sometime around the year 199. The trail goes cold from there, and some 150 search expeditions have failed to pick it up. Most researchers believe Alexander’s grave is still lurking somewhere in Alexandria, but others argue that it may have been moved to Venice, Greece or some other location in Egypt.