Cold War US spy satellite images reveal nearly 400 undiscovered Roman forts

• Satellite images taken during the Cold War have revealed almost 400 previously unknown Roman forts.
• The findings were published in Antiquity, an academic journal focusing on archaeology.
• They suggest that Rome's eastern frontier was a hub of trade rather than a defensive border.

Satellite images taken during the Cold War have revealed almost 400 previously undiscovered Roman forts across Iraq and Syria, archaeologists said.

The research, published in Antiquity, an academic journal that focuses on archaeology, has forced historians and archaeologists to re-evaluate their understanding of Rome's eastern front, 1,900 years ago.

The area was previously surveyed by Antoine Poidebard, a French Jesuit priest who pioneered aerial archaeology in the 1920s. He mapped 116 Roman forts along a 1,000 km, or roughly 620-mile, border, suggesting that these represented a defensive line against Arab and Persian invaders due to their spacing. 

The new research found a further 396 previously undiscovered forts, suggesting that the region was more likely a hub of global trade.

The findings suggested that the forts were used to "support movement of people, goods, and military assets between east and west," Jesse Casana, the lead author of the study and a professor of anthropology at Dartmouth College, shared with Insider.

Casana's team now has a simple question: was it "a wall or a road?"

Previous theories had imagined the forts as defining a north-south defensive border, but the newly discovered forts a showed an "east-west trending line connecting the Tigris River with the Mediterranean," Casana said.

Cold War imagery 

The photographs used in the study came from declassified spy images from the CORONA and HEXAGON satellite programs.

CORONA, which started in the late 1950s, was designed to search images of the Earth's surface "for answers to the nation's pressing intelligence questions." It became the "single most important source of intelligence on Soviet strategic forces," according to the CIA.

HEXAGON saw the "largest and last" US intelligence satellites bring photographic film back to earth, capturing "877 million square miles of the Earth's surface between 1971-1986," per the National Museum of the United States Air Force. Analysts used the images to identify potential threats.

Casana said the "next steps should be to expand this kind of research both to other regions of the world, as well as using additional types of imagery."