Archaeologists have uncovered a mysterious enclosure hidden deep inside the Great Pyramid of Giza, the oldest of the seven wonders of the ancient world.
The massive cavity stretches for at least 30 metres and lies above the grand gallery, an impressive ascending corridor that connects the Queen's chamber to the King's in the heart of the historic monument. It is the first major structure found in the pyramid since the 19th century.
It is unclear whether the void is a chamber or a corridor, or whether it played any more than a structural role in the pyramid's construction – such as relieving weight on the grand gallery below. But measurements show that it has similar dimensions to the grand gallery, which is nearly 50 metres long, eight metres high and more than a metro wide.
Scientists discovered the void using sensors that detect particles known as muons, which rain down on Earth when cosmic rays slam into atoms in the upper atmosphere. The muons travel at close to the speed of light and behave much like x-rays when they meet objects. Armed with suitable equipment, researchers can used them to reveal the rough internal structure of pyramids and other ancient monuments.
"We know that this big void has the same characteristics as the grand gallery," said Mehdi Tayoubi at the HIP Institute in Paris, a non-profit organisation that draws on new technology to study and preserve cultural heritage. "It's really impressive."