Thought to be a gigantic tomb built for the the pharaoh Khufu over a 10 to 20-year period that ended somewhere around 2560 BC, the Great Pyramid of Giza in Egypt is the single remaining vestige of the Seven Wonders of the Ancient World. When it was first built it was 146.5 metres high, before crumbling to 138.8 metres tall, where it stands now.
There are three known chambers in the Great Pyramid - the base chamber sits on the bedrock and supports the rest of the pyramid, while the upper two chambers are called the Queen’s and King’s Chambers. Extending from the north and south walls of the Queen’s Chamber are two tunnels - about 20 cm by 20 cm - that are blocked off by stone doors. No one knows what these tunnels were originally intended to do, but one theory is that they led to a secret chamber.
According to Rowan Hooper at New Scientist, researchers have tried several times to send little robots into the Great Pyramid to solve this mystery. In 1993, a robot made it 63 m up the south wall tunnel to find a small pair of stone doors set with metal pins. This was strange enough on its own, because metal was not found in any other part of the Great Pyramid, so what function was it performing here? Door handles, perhaps? Or a key?
Almost a decade after that, another robot drilled into a stone block in the tunnel and found a small, strange empty chamber that ended with a large stone block.
This year, a team of engineers led by Rob Richardson from the University of Leeds in the UK decided to further investigate this mystery, and developed a new robot to help them explore the chamber. They got it to crawl up into the tunnel, and use its flexible “micro snake” camera to see into and around all the nooks, crannies and corners. What this robot found was 4,500-year-old hieroglyphs written in red paint, and carvings in the stone that could have been made by the stone masons at the time the chamber was being built.
"Red-painted numbers and graffiti are very common around Giza,” added Egyptologist Peter Der Manuelian from Harvard University and director of the Giza Archives at the Museum of Fine Arts in the US. "They are often masons' or work-gangs' marks, denoting numbers, dates or even the names of the gangs."
The robot was also able to get its stretchy camera in and around the mysterious empty chamber to get a look at the back of the stone door for the first time. This allowed it to film parts of the metal pins that had never been seen before, and their beautifully looped tips suggest that rather than being functional, they were probably just ornamental features.
Egyptologist Kate Spence from the University of Cambridge in the UK, who was not involved in the study, says it’s almost certain that these tunnels were made to be symbolic rather than functional. "The metal pins look like symbolic door handles, and the shafts from the Queen's Chamber are oriented north-south, not east-west, so I strongly suspect that their function is symbolic and relates to the stars, not the sun," she told New Scientist.