The oldest fortified settlement in North America has been discovered in Georgia, giving insights into the early colonization of the New World, researchers say.

Fort Caroline, a long-sought fort built by the French in 1564, had long been thought to have been built near modern-day Jacksonville in Florida, but researchers say its actual site has been discovered 70 miles to the north -- in Georgia.

The site is on an island at the mouth of the Altamaha River, two miles southeast of the city of Darien, they said.

"This is the oldest fortified settlement in the present United States," historian and Florida State University alumnus Fletcher Crowe said. "This fort is older than St. Augustine, considered to be the oldest continuously inhabited city in America. It's older than the Lost Colony of Virginia by 21 years; older than the 1607 fort of Jamestown by 45 years; and predates the landing of the Pilgrims in Massachusetts in 1620 by 56 years."

To make the discovery, Crowe flew to Paris and conducted research at the Bibliotheque Nationale de France, the French equivalent of the U.S. Library of Congress, where he found a number of 16th-century maps that pinpointed the location of Fort Caroline.

Some of the maps were in 16th-century French, some in Latin, some in Spanish, and some were even in English, he found.

Crowe was able to match French maps from the 16th to 18th centuries of what is today the southeastern coast of the United States with modern charts from the National Oceanic and Atmospheric Administration and the U.S. Geological Survey.

Although the site has been confirmed, it has not yet been excavated by archaeologists, a release from Florida State University said.