After 25 years of fieldwork abroad, UNC-Chapel Hill archaeologist Scott Madry has dug up a new way to hunt for ancient ruins -- without leaving home.

Last year, Madry read how an Italian man accidentally discovered the outline of an ancient Roman villa while looking at his house on Google Earth. Since then, with help from the French government, Madry has confirmed the free service's promise as a research tool. As the news spreads, other scientists are growing excited, too.

"This is very fascinating for us. There is great potential," said Axel Posluschny of the German Archaeological Institute in Frankfurt. Posluschny, like Madry, researches ways that computers can help archaeologists.

Google Earth, a sister product to the Internet's most popular search engine, collects and displays satellite images taken around the globe. Some have high enough resolution to let viewers see people standing outside. Most viewers download pictures for play, enjoying bird's-eye views of home, the old neighborhood, exotic places they would like to go.

Madry looks for things that are difficult to see on the ground, usually from airplanes or in aerial photographs. Altered ground can preserve the outlines of things people built centuries ago.

For 25 years, Madry has scrutinized such details to explore how a Celtic people called the Aedui lived in France for about three centuries starting about 300 B.C. It is hard to find new clues.

After reading about the Italian man's good luck, Madry got out his laptop, fired up Google Earth and looked over lands in Burgundy near his research area. Google Earth displays that area in particularly good resolution. Immediately he spotted features that, to his trained eye, resembled outlines of Iron Age, Bronze Age, ancient Roman and medieval residences, forts, roads and monuments.

"I've spent 25 years in this region of France," Madry said. "In the whole time, I've found a handful of archaeological sites. I found more in the first five, six, seven hours than I've found in years of traditional field surveys and aerial archaeology."

Sightings confirmed

In all, he recorded 101 possible ancient sites along with their longitudes and latitudes. This spring, he visited the French Ministry of Culture's archaeology office in Dijon to compare what he found on the Internet with what the French have found on the ground. The government files confirmed his hunch.

About 75 percent of his computer-screen finds were known archaeological sites, proving that what look like ancient remains on the Internet can be bona fide finds. A share of the remaining 25 percent could be new sites that -- until now -- have escaped discovery.

Everything Madry downloaded was free. When he reported preliminary findings at the international Computer Applications and Quantitative Methods in Archaeology conference this spring, other researchers took notice. Those who work in countries where aerial photographs are forbidden or restricted for security reasons are particularly curious. Madry was encouraged to teach the technique at next spring's gathering.

The images can be fun

Chikai Ohazama, a Google Earth product manager in Mountain View, Calif., said his company posted the satellite images beginning in 2005 to widen access to technology that was once the domain of very few.

Since it reached the Web, people have had their fun with it -- finding and sharing images of airplanes that satellites captured around the world or pinpointing every location ever mentioned in a play by William Shakespeare.

Serious missions employ it as well, Ohazama said. After Hurricane Katrina, Google took pains to quickly update images of the Gulf Coast and New Orleans. Evacuees and others looked there regularly to witness the damage.

Ohazama said he wasn't aware of Madry's work, though the archaeologist has disclosed his project to the company. But Google likes to be surprised by people's creativity, he said.

"It's a platform we don't want to control," Ohazama said.