Pyramids

 The Pyramids of Egypt

As unexplained mysteries go, the pyramids of Giza in Egypt really are something special. We still don't really know how the Egyptians built the largest pyramid of all, known as the Great Pyramid of Cheops (or Khufu), some 5,000 years ago. Remember, this was even before the invention of the wheel!

The Pyramid of Cheops is the size of a 40-storey building and covers an area big enough to fit 10 football fields in it. More than 2 million stone blocks were used to make the pyramid, each weighing 2-5 tons and cut from a distant limestone quarry on the other side of the Nile. Experts reckon it took 400,000 men some 20 years to complete.

Engineering feats aside, there are still some unexplained mysteries going on at the Pyramid of Cheops. In the 1940s, a French hardware dealer spotted some mummified animals exactly one-third up the height of the pyramid. The remarkable thing was they showed no signs of decomposition. He deducted that the pyramid shape was responsible for preserving these creatures.

Later, a Czech radio engineer conducted a series of experiments in which he placed a brand new razor blade inside a 1:1,000 scale model of Cheops. He aligned his pyramid on a north-south axis exactly like the real thing. After getting 50 shaves from the razor, he was forced to conclude that it was only getting sharper from being inside the pyramid. It took him 10 years to obtain a patent for this remarkable device, which still has no scientific explanation today.