A long-hidden narrow void in the Great Pyramid of Giza has been found by scientists in a discovery that could finally reveal the secrets of the 4,500-year-old monument.
The void stretches for at least 30 metres (100ft) above the Grand Gallery – an ascending corridor that links the Queen’s chamber to the King’s in the heart of the pyramid.
It is not known why the void exists or if there are any valuable artefacts inside as it is not obviously accessible.
But it has similar dimensions to the Gallery, which is 50 metres (164ft) long, eight metres (26ft) high and around a metre (3.2ft) wide.
Researchers suggest it could be a ‘construction gap’ – part of a trench that allowed workers to access the Grand Gallery and King’s Chamber while the rest of the pyramid was built.
The discovery was made after physicists took images of the inside of the pyramid using particles fired to Earth from space.
These cosmic particles penetrate the rock in a similar way to X-rays, only much deeper.
The collaborative effort, between archaeologists, historians and physicists, has been hailed as the biggest discovery inside the Giza landmark since the 19th century.
Made under the watch of the Pharaoh Khufu and completed in around 2550 BC, Egypt’s Great Pyramid, or the Pyramid of Giza, served as the world’s tallest man-made construction for thousands of years.
The structure, also known as Khufu’s Pyramid, is the sole survivor of the ancient Seven Wonders of the World.
How it was built has long been a bone of academic contention and there is no universal agreement about its creation.
Scientists say the latest discovery, published in the journal Nature, could help shed light on its construction.
To find out more about the pyramid, researchers from countries including France and Japan began a project to scan the structure in October 2015.
The scientists made the discovery using cosmic-ray imaging, recording the behaviour of subatomic particles called muons that penetrate the rock.
Detectors were set up inside the pyramid, including in the so-called Queen’s Chamber.
This allowed the pyramid’s insides to be seen without physically disturbing it, as the results showed empty space differently from rock.
The presence of the space, dubbed the ScanPyramids Big Void, was confirmed using three different detection technologies over several months after first being spotted, the paper said.
The results were then analysed three times.