Archaeologists discover an ancient defense mechanism inside the great pyramid of Giza

The ancient pyramids of Egypt served as tombs for the great rulers and their families, but did you know they also served as fortresses?

According to Egyptologist, Mark Lehner, the series of grooves on the walls just outside King Kufu's chamber in the great pyramid hold the key.

"Khufu's builders designed a line of defense against anyone who'd enter the King's chamber, had they got this far," he said.  "These grooves and protrusions are not decorative. They are part of a very primitive machine."

Using the grooves, three large stone slabs would be slid into place to blockade the king's chamber if there were times of trouble.  All handled by workers, other slabs would be put further down the passageway to blockade it and the passageway was sealed with limestone.

Even with all the defense, the tomb was "probably already robbed of its contents sometime between the end of Khufu's reign and the collapse of the Old Kingdom [around 2134 BC]," writes Lehner in his book The Complete Pyramids.

Future research of the pyramids include sending robots deep inside, searching for secret passageways and actually using cosmic rays to map the interior.