Analysis of sand particles trapped in the tiny cracks on some of the sledges suggests they were used to transport limestone blocks weighing tens of tonnes to the building site of Giza's Great Pyramid, 4,500 years ago.
Scientists, led by researchers at the University of Amsterdam, say that as the sleds moved, they would have compacted the sand beneath their runners. This process causes changes to the sand's magnetic properties, creating a trail that can be mapped.
The team say the technique allowed them to map a network of "hidden ramps" around the pyramids that were possibly used to haul building materials.
The Great Pyramid of Giza, also known as the Pyramid of Khufu, is the oldest and largest of the three pyramids in the Giza Necropolis in Egypt. It is believed to have been constructed in the 25th century BC and was built using limestone and granite.
The pyramids at Giza are some of the most impressive and iconic structures in the world. They were built using huge stone blocks, some of which weigh up to 20 tonnes. How these stones were moved into place remains a mystery.
