An Australian archaeologist has used Google Earth to uncover hundreds of huge, mysterious stone structures in Saudi Arabia.
David Kennedy has documented almost 400 of the stone structures dating back thousands of years, with a few of these wall-like formations sitting on top of old lava domes - the remains of volcanic lava flows.
Kennedy set up the Aerial Photographic Archive for Archaeology in the Middle East - an initiative to map the area that now has more than 140,000 aerial images, Metro UK reports.
Through the development of Google Earth, he has been able to expand the database and use it to find the previously undiscovered stone structures.
His analysis, which will appear in the forthcoming issue of Arabian Archaeology and Epigraphy, indicates the structures are known to the Bedouin as “Works of the Old Men”.
The structures bare a striking resemblance to others found in the Middle East that are known as "gates".
Their purpose is unknown but these new gates are unlike anything else previously found.
“Identification, mapping and preliminary interpretation imply an early date in the sequence of the works—perhaps the very earliest—but no obvious explanation of their purpose can be discerned,” the study says.
“It is impossible at the moment to date these gates except relatively. I have argued in the article that they are the earliest of the so-called ‘Works of the Old Men’, the stone-built structures found widely in ‘Arabia’ from northern Syria to Yemen, but especially common in the lava fields,” he told Newsweek.
The longest gate in the Harrat Khaybar region measures 518 metres in length, while the shortest is 12.8m.
"It is crying out for close examination on the ground to see if there are associated artefacts,” Kennedy said.
Researchers say it will be imperative to find out more.