Archaeolgists have used Google Earth to spot hundreds of mysterious, seemingly ancient man-made structures in the sands of Saudi Arabia.
The archaeologists first spotted the structures in Google Earth imagery – and have now spotted clusters in a region of Saudi Arabia called Harrat Khaybar.
Some are four times the length of a football pitch, and some experts have suggested that they may be up to 7,000 years old.
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The archaeologists refer to them as ‘gates’ because of how they look like garden gates from above – but their purpose, and age, remains unknown.
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David Kennedy of the University of Western Australia wrote, according to LiveScience that the gates, ‘appear to be the oldest man-made structures in the landscape.
He wrote, ‘Gates are found almost exclusively in bleak, inhospitable lava fields with scant water or vegetation, places seemingly amongst the most unwelcoming to our species.’
Some of the gates are sufficiently old that lava flows appear to go over them.
The gates are up to 1,700 feet long, Kennedy writes.
Kennedy has spotted hundreds of archaeological sites in the area, mainly using Google Earth imagery – as it’s difficult for researchers to access sites on the ground.