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Stuff keeps getting older: an upcoming article in the journal Arabian Archaeology and Epigraphy will discuss the discovery of almost 400 mysterious stone structures at Harrat Khaybar, in west-central Saudi Arabia. The structures are believed to be around 7000 years old (that’s more than 2000 years older than the pyramids of Egypt).

Dubbed ‘gates’ by those studying them, as they look like fence gates when viewed from above, the structures are actually low, stone walls that “appear to be the oldest man-made structures in the landscape”,according to the author of the paper, Professor David Kennedy. “No obvious explanation of their purpose can be discerned.”

The smallest of the gates extends about 43 feet (13 meters), while the longest is 1,699 feet (518 m) long, or longer than an NFL football field. Many have multiple stone walls that, in some instances, form a rectangular design; some of the others, called “I” type gates, have only one stone wall with heaps of stone at each end. “Gates are found almost exclusively in bleak, inhospitable lava fields with scant water or vegetation, places seemingly amongst the most unwelcoming to our species,” Kennedy wrote.

Some of the rock structures are even built on the side of old lava domes, and are partially covered by lava flows, indicating they are older than those flows.

Though many of the recent discoveries have been made through satellite surveys, the gates were noticed way back in the 1980s by volcanologists mapping the area. And some of the primary investigative work on the structures has been done by a group of Saudi Arabian citizens known as Desert Team. I highly recommend heading over to their site and browsing their webpage – they have posted an amazing number of photos showing these sites – and other, even more bizarre shaped structures – both from the sky, and on the ground. While most of the content is in Arabic, you can use Google Translate to get a good idea of the original text. And it’s worth noting, despite this being a ‘breaking’ story in the English world, these photos are from 2008.

For instance, here are a few other structures, which they’ve dubbed ‘comets’ and ‘triangles’, which range from tens to hundreds of metres in length (credit for all photos below to alsahra.org):

And the ground photos give a different perspective entirely, such as this photo showing one of the ‘triangles’ above:

Interestingly, other ground-level photos appear to show some rocks that are a lot more regular in shape, perhaps suggesting that they were tooled into the rectangular shape?

No formal archaeological fieldwork has yet been conducted on the gates, so no doubt there is still much to learn about them. Could they be a variation on desert kites, similar structures in the area that are known to have been used for trapping animals? Or are they burial monuments similar ancient stone structures in other parts of the world? Another site for Graham Hancock to investigate perhaps?

Read more about the structures at Live Science, and as I said, be sure to check out the amazing images and information at the alsahra.org website. And if you want to ‘fly’ around the area taking a look at the structures, check out the Google Maps embed below.