Today Google celebrates the 115th birthday of aviatrix Amelia Earhart -- and one of the great unsolved 20th-century mysteries.

Sorry, Amelia, no birthday present this year. But it's not been for a lack of trying.

Throughout the years there have been a number of search attempts to find Earhart or wreckage of her plane. Now 75 years after she vanished in her Lockheed Model 10 Electra over the Pacific Ocean, the most recent hope of finding evidence of Earhart's plane is fading.

Discovery News reported last week that a $2.2 million expedition by The International Group for Historic Aircraft Recovery (TIGHAR) came to an end due to the challenges of exploring a steep, underwater coral cliff.

You remember, a couple of months ago, Secretary of State Hillary Clinton held a press conference, and gave an boost to the credibility to the TIGHAR hunt for Earhart's plane.

TIGHAR researchers believed that when Earhart and her navigator Fred Noonan went missing July 2, 1937, they made an emergency landing on a reef near the uninhabited island Nikumaroro.

Beginning in the 13th century, the Mongol Empire spread across Asia and into the Middle East like wildfire, growing into the largest contiguous land empire the world has ever seen.

Historians have long speculated that periods of drought pushed the Mongol hordes to conquer their neighbors, but preliminary new findings suggest that theory may be exactly backward. Instead, consistent rain and warm temperatures may have given the Mongols the energy source they needed to conquer Eurasia: grass for their horses.

This idea, bolstered by the discovery of tree rings that preserve a climate history of Mongolia back to 657 A.D., is still in the preliminary stages of investigation.

LiveScience spoke with Amy Hessl, the dendochronologist, or tree-ring researcher, who along with collaborators Neil Pederson and Baatarbileg Nachin first discovered the preserved trees hinting at the weather during the era of the Mongols.

Deep-sea explorers have pulled up 48 tons of silver treasure from three miles below the surface of the North Atlantic in what may be the deepest, largest precious metal recovery in history.

The haul was retrieved from the S.S. Gairsoppa, a 412-foot steel-hulled British cargo ship that sank in February 1941.

The expedition, by Odyssey Marine Exploration, a company specializing in shipwreck exploration, recovered 1,203 bars of silver, totaling 1.4 million ounces. Viewers will have the chance to follow the pursuit of the lost treasure on an upcoming Discovery Channel special produced by JWM Productions.

The cache has been transported to a secure facility in the United Kingdom, which contracted the project under the Department of Transport. Under the contract, Odyssey will retain 80 percent of the net value of recovered goods, after expenses, according to a press release.

You'd think that archaeologists would have unearthed everything that needs unearthing by now. An 8th century military town is believed to have been discovered in Germany. Specialists can't be sure at this point because the settlers weren't considerate enough to leave a map or a sign, but artifacts and other features are being used as conclusive evidence.

The demolished city is thought to be long-lost Sliasthrop, which was used as a military base. Thirty of the 200 houses have been properly excavated and have revealed a lot about how military towns functioned. A large building, comparable to a modern day community center, was found with arrow heads embedded in its charred walls, meaning that is was attacked, probably during a battle.

A team of archaeologists has uncovered a temple near part of the Maya archaeological site at El Zotz, Guatemala. The structure was likely built after the tomb to honor the leader buried there.

The team, led by Brown University's Stephen Houston, began uncovering the temple, called the Temple of the Night Sun, in 2009. The ornately decorated structure is topped by a temple covered in a series of masks depicting different phases of the sun, as well as deeply modeled and brightly painted stucco throughout. Dating to about 350 to 400 A.D., the temple sits just behind the previously discovered royal tomb, atop the Diablo Pyramid.

"The Diablo Pyramid is one of the most ambitiously decorated buildings in ancient America," Houston said in a prepared statement. "The stuccos provide unprecedented insight into how the Maya conceived of the heavens, how they thought of the sun, and how the sun itself would have been grafted onto the identity of kings and the dynasties that would follow them." The well preserved find is giving investigators a larger amount of new information revealed about the Maya civilization.

This latest discovery was made public July 18, 2012, during a press conference in Guatemala City, hosted by the Instituto de Antropologia e Historia de Guatemala, which authorized the work.

The Maya later built additional levels on top of the original structure, which helped to preserve the stuccos, but this also makes excavation more difficult. While excavating the tomb in 2009, Houston and his team discovered a small portion of the carvings peeking out from thieves' tunnels that had been dug several decades earlier. The archaeologists have only been able to clear narrow tunnels around the building to get a look at the masks and other carvings. There are several sections, including whole sides, an area of the roof, and the base still to be excavated. More than 70 percent of the temple is still to be uncovered.

It's the face that launched a thousand imitations. Now, archaeologists are convinced they've found the body of the real Mona Lisa.Buried in a crypt beneath a convent in Florence, Italy, archaeologists believe they have uncovered the skeleton belonging to the model who posed for Leonardo da Vinci's masterpiece in 1504.

The wife of a rich silk merchant, Lisa Gheradini, is generally accepted by historians to be the woman with the mysterious smile.

Lisa Gheradini, whose married name was Giocondo, became a nun after her husband's death. She was buried in the grounds of the Convent of Saint Ursula where she died in 1542, aged 63.

Archaeologists had to dig through thick concrete laid as part of an effort to turn the convent into barracks for soldiers.

But they quickly unearthed a female-sized human skull, along with fragments of vertebrae and ribs

Neanderthals have long been viewed as meat-eaters. The vision of them as inflexible carnivores has even been used to suggest that they went extinct around 25,000 years ago as a result of food scarcity, whereas omnivorous humans were able to survive. But evidence is mounting that plants were important to Neanderthal diets - and now a study reveals that those plants were roasted, and may have been used medicinally.

The finding comes from the El Sidrón Cave in northern Spain, where the roughly 50,000-year-old skeletal remains of at least 13 Neanderthals (Homo neanderthalensis) have been discovered. Many of these individuals had calcified layers of plaque on their teeth. Karen Hardy, an anthropologist at the Autonomous University of Barcelona in Spain, wondered whether it might be possible to use this plaque to take a closer look at the Neanderthal menu.

Using plaque to work out the diets of ancient animals is not entirely new, but Hardy has gone further by looking for organic compounds in the plaque. To do this she and a team including Stephen Buckley, an archaeological chemist at the University of York, UK, used gas chromatography and mass spectrometry to analyse the plaque collected from ten teeth belonging to five Neanderthal individuals from the cave.

The plaque contained a range of carbohydrates and starch granules, hinting that the Neanderthals had consumed a variety of plant species. By contrast, there were few lipids or proteins from meat.

Hardy and her colleagues also found, lurking in the plaque of a few specimens, a range of alkyl phenols, aromatic hydrocarbons and roasted starch granules that suggested that the Neanderthals had spent time in smoky areas and eaten cooked vegetables. The results are published today in Naturwissenschaften¹.

"The idea that Neanderthals were largely meat-eaters has been hard for me to accept given their membership in a mainly vegetarian clade. It is exciting to see this new set of techniques applied to understanding their palaeo-diet," says Richard Wrangham, an anthropologist at Harvard University in Cambridge, Massachusetts.

A historic letter indicates the Nazis planned to assassinate Sir Winston Churchill, the British wartime prime minister, with a bar of exploding chocolate.

A Nazi plot to kill Sir Winston Churchill with a bar of exploding chocolate during the Second World War has been revealed in historic papers.

Giving a new meaning to the dessert name "death by chocolate", Adolf Hitler's bomb makers coated explosive devices with a thin layer of rich dark chocolate, then packaged it in expensive-looking black and gold paper.

The Germans apparently planned to use secret agents working in Britain to discreetly place the bars - branded as Peters Chocolate - among other luxury items taken into the dining room used by the War Cabinet during the conflict.

The lethal slabs of confection were packed with enough explosives to kill anyone within several metres.

But the plot was foiled by British spies who discovered the chocolate was being made and tipped off one of MI5's most senior intelligence chiefs, Lord Victor Rothschild, before the wartime prime minister's life could be endangered.

A rare stash of gold coins was discovered hidden beneath a floor tile in a fortress outside Tel Aviv.

Israeli archeologists this week discovered one of the largest gold stockpiles ever found while digging in an ancient castle that hosted some of the major battles of the Crusades.

The cache - discovered in a broken pottery vessel hidden under a floor tile - contained 108 gold coins which archeologists have estimated to be worth over $100,000. Researchers told UPI that crusaders probably hid the treasure trove from invading Muslim conquerors in the mid 13th Century.

The remains of a magnificent ancient harbor have emerged from a dig in Akko (Acre), a city at the northern tip of Haifa Bay in Israel.

Dating back to the Hellenistic period (third-second centuries BC), the port was Israel's largest and most important at the time.

Archaeologists at the Israel Antiquities Authority made the discovery as they unearthed large mooring stones that were incorporated in the quay. They were used to secure sailing vessels that anchored in the harbor about 2,300 years ago.

In some of the stones the archaeologists found a hole for inserting a wooden pole - - probably for mooring and/or dragging the boat.

This was most likely a military harbor, according to Kobi Sharvit, director of the Marine Archaeology Unit of the Israel Antiquities Authority,

"A find was uncovered recently that suggests we are excavating part of the military port of Akko. We are talking about an impressive section of stone pavement about 8 meters long by about 5 meters wide," Sharvit said.

Delineated on both sides by two impressive stone walls built in the Phoenician manner, the floor sloped slightly toward the south. The archaeologists found a small amount of stone collapse in its center.