Newly-discovered roads of the Roman Empire

A high-res map nearly doubles the known extent of the first continent-scale road network ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­

June 2, 2026—A new high-resolution map nearly doubles the number of roads in the Roman Empire. Plus, the oldest human art in the U.K. and mathematicians try to rein in AI. —Andrea Gawrylewski Chief Newsletter Editor TODAY'S NEWS “Rediscovered Late Upper Palaeolithic Painted Imagery at Bacon Hole, Gower Peninsula, South Wales,” by George H. Nash et al., in Quartenary, Vol. 9, No. 3. Published online May 26, 2026 For 100 years, scientists thought these red markings inside a cave in Wales were natural. Now a new analysis suggests they were made deliberately by ancient humans some 17,000 years ago and therefore are the oldest cave art ever discovered in the U.K. | 2 min read Hyperbaric oxygen therapy is being explored as a treatment for long COVID. Here’s what the research shows. | 4 min read A group of mathematicians, computer scientists, and math historians have released guidelines for the use of AI in their disciplines. | 3 min read  The NSF has begun dismantling the Ocean Observatories Initiative, a network of 900 deep-sea instruments which for the past decade has collected crucial data on physical, chemical, geological and biological conditions from all layers of the Atlantic and Pacific oceans. | 2 min read President Trump’s executive order fast-tracks research into the medical use of psychedelics. It will certainly open the door to experimenting with psychedelic therapies for children and eventually prescribing them, experts say. | 6 min read  Another presidential executive order asks technology companies to voluntarily share new AI models with the government for up to 30 days before releasing the models more widely. | 2 min read A deadly Ebola outbreak has killed hundreds and is spreading fast in Africa. The muted U.S. response is alarming experts. | 12 min podcast New observations of B-meson decay—known as a penguin decay—at the Large Hadron Collider at CERN point to a whole new kind of physics. | 5 min read More News Every subscription helps fund the stories, reporting and delightfully strange science behind this newsletter. Start your Scientific American subscription: 90 days for just $1. TOP STORIES The Via Appia, constructed starting in 312 B.C.E., is the oldest and best-known road of the Roman Empire. Stefano Valeri/Alamy On the Roman Roads A new map of Roman roads suggests that the ancient Roman Empire built more than 300,000 kilometers of roads, more than double the previous estimate. The roads span an area the size of the European Union in a network that allowed the flow of people, goods, ideas and disease from Egypt to Germany, Spain to Turkey. Historically, archaeologists have used the physical remnants of the roads and historical documents to estimate the locations of these ancient paths. But the researchers behind this new project combined information from historical datasets plus modern topographical maps and satellite data to form a high-definition online atlas, called Itiner-e.   Researchers found 8,000 kilometers of roads whose locations are known with certainty and 292,000 kilometers of roads that rely on varying degrees of conjecture. Daniel P. Huffman How they did it:  Milestone digitization: For every 1,000 “paces” (one pace = about 5 Roman feet) on a road, the ancient Romans placed a labeled rock “milestone” to help travelers understand where they were. These milestones have been hugely helpful to modern archaeologists as they retrace the locations of ancient Roman roads. By aggregating databases that include more than 8,000 milestone locations and 14,000 ancient places, the Itiner-e team started their process of connecting these dots into the roads they once were.  Historical satellite photography: Some of the ancient roads are no longer visible today. For example, the ancient city of Samosata (in present-day Turkey) was flooded by a dam in the 1980s. But declassified photos from cold war–era satellites helped the researchers see what the roads there looked like before they were flooded. This is also true for other roads that have long since been destroyed by urbanization or other changes.  Topography: Detailed topographic maps—typically made for military strategy—also helped inform the precise shape of roads along mountains or other pre-developed landscapes. Taking the shape of the landscape into account helps researchers map the roads more precisely. Paleogeography: The sediment near these ancient roads also helped the researchers reconstruct the landscapes. In some parts of the map, like in the Netherlands, the current canalized landscape doesn’t match the marshy landscape it once was. Dutch researchers on the project used paleogeography to identify old, abandoned riverbeds and locate the dry land between settlements that could have supported roads.  The Romans used milestones, such as this one on the Via Domitia in Herault, France, across the Empire to inform travelers of their location and distance. These stone markers can be used to reconstruct the paths of Roman roads. Hemis/Alamy What the experts say: Despite seeing the full scope of the network, researchers know the precise location of only 2.7 percent of it. They created a “confidence map” that describes the varying certainty they have on the location of the roads across the map. “It essentially charts our ignorance,” writes Tom Brughmans, one of the co-directors of the project and an archaeologist at Aarhus University in Denmark. As remarkably precise and thorough as this map is, “as researchers, we must be open and explicit about what is observed and what is informed conjecture.” —Emma Gometz, newsletter editor

PUZZLER Can you unscramble this image of our cover from the July 1986 issue? This cover shows an F-16 pilot using a flight simulator, a system that is increasingly employed to help train pilots for the flight tasks traditional training might not cover.  The Romans did not invent roads. But they knew a good thing when they saw it and went about expanding and scaling up thoroughfares throughout their expanding empire. This enabled unprecedented movement of goods and resources among city centers and rural areas. Humans have always depended on close personal bonds, but we seem equally driven to build connections across ever-greater distances—exchanging ideas, culture and opportunity along the way. Thanks for reading and send any feedback to: newsletters@sciam.com. Until tomorrow!   —Andrea Gawrylewski, Chief Newsletter Editor

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