 Five world mysteries that we can't explain. Few stories have the power to captivate us more than those that remain unresolved. Codes, puzzles, and cryptic public art tease us with their intrigue. Why is their message coded? What great secrets might they hide? Despite the efforts of our most revered historians, cryptographers, and determined treasure hunters, history is replete with riddles that continue to confound us today. Number five, the lost city of Atlantis. Atlantis is a legendary lost island subcontinent, often idealized as an advanced utopian society holding wisdom that could bring world peace. The idea of Atlantis has captivated dreamers, occultists, and new ages for generations. Unlike many legends whose origins have been lost in the midst of time, we know exactly when and where the story of Atlantis first appeared. The story was first told in two of Plato's dialogues, written about 330 BC. Though today Atlantis is often thought of as a peaceful utopia, the Atlantis that Plato described in his fable was very different. A technologically sophisticated but morally bankrupt evil empire, Atlantis attempts world domination by force. The only thing standing in its way is a relatively small group of spiritually pure, morally principled, and incorruptible people, the ancient Athenians. Overcoming overwhelming odds, the Athenians are able to defeat their far more powerful adversary simply through the force of their spirit. At four, the Wow signal. One summer night in 1977, Jerry Amon, a volunteer for SETI, or the search for extraterrestrial intelligence, may have become the first man ever to receive an intentional message from an alien world. Amon was scanning radio waves from deep space, hoping to randomly come across a signal when he saw his measurements spike. The signal lasted for 72 seconds, the longest period of time that could possibly be measured by the array that Amon was using. It was loud and appeared to have been transmitted from a place no human has ever gone before. 120 light years away in the constellation Sagittarius near the star called Tau Sagittari. Amon wrote the words Wow on the original printout of the signal, thus its title as the Wow signal. All attempts to locate the signal again have failed, leading to much controversy and mystery about its origin and its meaning. And number three, the Black Knight Satellite. This artificial satellite has caused major media interest since the late 50s and has become one of the most talked about objects in space. First thought to be a Russian spy satellite, the Black Knight Satellite has gripped the interests of millions worldwide. According to monitoring agencies around the world, the Black Knight Satellite has been transmitting radio signals for over 50 years now. The USA and Soviet Union have shown particular interest in this unidentified space object. Rumors are that it was Nikola Tesla who was the first man to intercept a signal from the Black Knight Satellite in 1899 after he built a high voltage radio device in Colorado Springs. Since the 1930s, astronomers worldwide have been reporting strange radio signals which allegedly come from the Black Knight. In 1957, Dr. Luis Carlos of the Communications Ministry in Venezuela photographed him while taking pictures of Sputnik II as it passed over Caracas. It was the ham radio operator who apparently decoded a series of signals received from the UFO Satellite and interpreted it as a star chart centered on the Epsilon Boot Star System. According to the decoded message, the Black Knight Satellite originated from the Epsilon Boot Star System 13,000 years ago. On August 23, 1954, the Technology Magazine Aviation Week and Space Technology released a story about the Black Knight Satellite. This story angered the Pentagon, who apparently was trying to keep the information secret. At number two, the Bermuda Triangle. The Bermuda Triangle is a mythical section of the Atlantic Ocean roughly bounded by Miami, Bermuda, and Puerto Rico. Hundreds of ships and airplanes have mysteriously disappeared in this area. Unexplained circumstances surround many of these accidents, including one in which the pilots of a squadron of U.S. Navy bombers became disoriented while flying over the area. The planes were never found. Other boats and planes have seemingly vanished from the area in good weather without even issuing a radio distress message. The area referred to as the Bermuda Triangle, or Devil's Triangle, covers about 500,000 square miles of ocean off the southeastern tip of Florida. When Christopher Columbus sailed through the area on his first voyage to the New World, he reported that a great flame of fire, probably a meteor, crashed into the sea one night and that a strange light appeared in the distance a few weeks later. He also wrote about erratic compass readings. And at number one on the list, Puma Punku. Puma Punku is truly a wonderful place. Not only is it an incredible temple complex filled with mysteries that baffle one's mind, it is a place where one loses the notion of space and time. This temple complex near Tiwanaku, Bolivia is one of the most incredible ancient ruins you will find in South America. Perhaps the biggest mystery involving Puma Punku, how did ancient mankind manage to transport these huge blocks of stones from quarries within 10 to 100 kilometers away? How did they manage to achieve precision cuts and how did they place the blocks in such a perfect manner? Engineers from around the world today still cannot answer nor replicate these achievements done by ancient mankind thousands of years ago. Another puzzling mystery of Puma Punku is the assembly of the walls. Each stone was finally cut to interlock with those surrounding stones and the blocks fit together like a puzzle, forming load-bearing joints without the use of mortar. The precision challenges today's engineering abilities. A common engineering technique is to cut the top of the lower stone at a certain angle and to place another stone on top of it cut at the same angle. The level of masonry we find at Puma Punku is just amazing. These stones look like as if they were cut with a laser. They are so precise and so smooth that you cannot come up with a logical explanation on how ancient man could have achieved this without the use of advanced modern equipment. It is simply a mystery.