Cliffhangers and Cryptograms: The Unsolved Mystery Quiz

Installed in 1991, Kryptos features four panels covered in code. The cryptic fourth panel has yet to be deciphered -- despite the fact that some of the world's best code breakers pass by it everyday.

Nine skiers were found dead in the Ural Mountains in 1959, an event known as the Dyatlov Pass Incident. Their tents were ripped open from the inside, and some suffered strange injuries. While some speculate that they were surprised by an avalanche, others pose more sinister explanations.

Searchers found a female skeleton on Nikumaroro in 1940. The bones were sent to Fiji for testing but were eventually lost, never to resurface, leaving the mystery of her fate still unresolved.

The Nazis snatched the legendary Amber Room from outside of St. Petersburg in 1941. Some speculate that it was destroyed in the war, while others believe it still lies hidden in some long-forgotten bunker.

Police near Adelaide found the body of a man in 1948. He carried no wallet and has yet to be identified. A scrap of paper in his pocket serves as the only clue to his identity, and features the phrase "Taman Shud," Persian for "It ended."

In 1971, D.B. Cooper demanded $200,000 and a pair of parachutes while on board a Northwest Airlines flight. He jumped out of the plane somewhere over the northwest U.S., never to be seen again. Though Cooper was never identified, scraps of the ransom money washed up in an Oregon river.

Since 1795, people have sought the fortune supposedly hidden beneath the ground on Oak Island in Nova Scotia. While some speculate that the hole contains pirate treasure or the Holy Grail, others believe it's simply a natural sinkhole containing nothing more exciting than dirt.

The Rapanui of Easter Island carved Rongorongo onto wooden tablets, but no one living on the island was able to decipher the language by 1860. Fun fact: Rongorongo alternates directions, so you must turn the tablet upside down after every line -- if you could actually read it, that is.

A cave in China contains a set of mysterious metal pipes, some more than a foot in diameter, which date back 140,000 years or more. Could the Baigong pipes serve as signs of extraterrestrial life or simply ironstone fossils that formed around long-dead trees?

The so-called lost colony left beyond a single word, Croatoan, carved into a tree. Did they fall victim to disease or violence -- or simply move in with the nearby Croatoan tribe that lived nearby?

Elizabeth Short was struggling to find work in film when she was murdered in Los Angeles in 1947. Her case remains one of the oldest unsolved murders in L.A. to this day.

This strange series of letters can be found at Shepard's Monument in Stafford, England. It's featured in "The Da Vinci Code," and some speculate it contains clues to the location of the Holy Grail.

You can find this puzzling 240-page text at Yale University. It contains elaborate illustrations and coded text. A high-resolution copy can be found on Yale's website if you'd like to take a crack at decoding it.

Known as "America's Stonehenge," the Georgia Guidestones contain some bizarre advice, including limiting the global population to less than half a billion. No one knows who commissioned the stones, and theories suggest everyone from the Illuminati to a satanic cult could be responsible.

Despite the fact that he claimed just 5 or 6 victims -- hardly prolific for a serial killer -- the case of Jack the Ripper continues to draw interest around the globe.

The vessel Mary Celeste was found floating at sea in 1872, her cargo intact, but her crew gone without a trace. To this day, no one knows what happened to the people onboard, or why they abandoned ship.

In the late 19th century, Thomas Jefferson Beale left a series of ciphers with a Virginia innkeeper. The yet-to-be-cracked code supposedly contains directions to a fortune in gold and silver hidden in Bedford County, Virginia.

Short wave radio station UVB-76 has broadcast series of beeps and buzzes from somewhere in Russia since the early '80s. Every few weeks, the transmission is interrupted by a creepy voice reading out a list of names.

Jimmy Hoffa likely met his end after that fateful meeting, but to this date, no one has managed to find his body.

The Wow signal got its name when scientist Jerry Ehman jotted his impressions of the sound on the paper output from the radio telescope he was manning at the time. The bizarre noise lasted 72 seconds and has never been repeated.