The Egyptian Pyramids continue to fascinate researchers and the general public alike with their mysteries, but we are getting closer and closer to unlocking all their secrets.

A particularly interesting feature was discussed in the recent Unearthed series on The Science Channel. During the program, Egyptologist Mark Lehner described a series of grooves found just outside King Khufu's burial chamber in the Great Pyramid. He believes the builders constructed a simple defense system: a series of thick granite blocks blocking the path to the chamber.

"Khufu's builders designed a line of defense against anyone who'd enter the King's chamber, had they got this far," said Lehner in the program.

"These grooves and protrusions are not decorative. They are part of a very primitive machine."

The grooves were used to direct slabs of granite towards the entrance as well as keeping them vertical. Another set of thicker blocks were to slide down the passageway, completely blocking the entrance from tomb raiders.

At least, that was the plan. The burial chamber 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 (Thames and Hudson, 1997). What is left of Khufu's burial is "just" a large red granite sarcophagus. But some archaeologists think that the burial chamber itself is a decoy and the real one remains hidden.

According to the Egyptian antiquity minister the pyramid could be hiding undiscovered cavities. In a statement back in 2011, he announced that scientists had “concluded the existence of several thermal anomalies that were observed on all monuments during the heating-up or the cooling-down phases [at sunset and at dawn]. To explain such anomalies, a lot of hypotheses and possibilities could be drawn up; presence of voids behind the surface, internal air currents."

The cavities might be natural (like cracks) or other undiscovered chambers. Exploration performed by robots, which went through the pyramid's six shafts (four originating in the king's chamber and two from the queen's chamber) discovered three copper doors. To fully understand if there are actual undiscovered chambers, scientists are using cosmic rays to map the interior of the pyramid.

Cheops Pyramid (Cheops being the greek name for Khufu) is one of the wonders of the ancient world and a unique and recognizable monument to human ingenuity. With or without a hidden chamber, perhaps Khufu is the one having the last laugh.

[H/T: Live Science]