Mysterious 'ancient stone gates' discovered in Saudi volcano field

Satellite imagery has revealed around 400 mysterious structures on the edges of volcanoes in Saudi Arabia's Harrat Khaybar region.

It is through that the stone structures, which have been described as "gates" due to their appearance from above, could be thousands of years old.

Some of the walls extend beyond the distance of four football pitches, while the smallest stretches to 43 feet.

The discovery has puzzled archaeologists, in part due to the structures' geographical positioning.

According to Professor David Kennedy of the University of Western Australia, the 'gates' "are found almost exclusively in bleak, inhospitable lava fields with scant water or vegetation, places seemingly amongst the most unwelcoming to our species."

He says that the walls "appear to be the oldest man-made structures in the landscape," adding that there is "no obvious explanation of their purpose." 

The recent find, however, is not the first of its kind in the Middle East.

Elsewhere in the region, mysterious stone structures have been found in the shapes og geometric patterns that appear to have astronomical significance.

One such example can be found in Jordan's Azraq Oasis, where the wheel-shaped structures are thought to align with the sunrise on the annual winter solstice. 

Professor Kennedy's paper on the recent find in Saudi Arabia is due to be published in the Arabian Archaeology and Epigraphy journal in November.