The first successful English settlement in what is now the United States got off to an unsteady start at a swampy island in a broad tidal river in 1607.
The 104 settlers of the Virginia Company named it Jamestown, after the sovereign whom more than half of them would die serving within a few months.
All traces of the fort, however, had been lost for more than two centuries.
The log fort had burned a year after it was built. Remains of the wall, along with any weapons, ceramics and other artifacts, were thought to have been washed away by the James River.
But archaeologists announced yesterday that the lost had been found.
In recent excavations, they uncovered stains of decayed wood where they said logs of the palisade wall had stood in the ground.
From this they established the three-sided fort's footprint, determining the outlines of a rounded bastion at one of the three corners and the angle at which the walls were joined.
Archaeologists said these observations conformed exactly with contemporary written descriptions of the original fort.
Archaeologists also reported finding traces of two buildings within the fort; evidence of glass-making and copper-working industries there; and thousands of other artifacts, including swords, armor, a smoking pipe, jewelry, ceramics and coins.
A grave at the site held the well-preserved skeleton of a white man in his early 20s who probably died of a gunshot wound, a fate raising intriguing questions about murder or mutiny or other tempests in the early colony.
In making the official announcement at Jamestown Island, Gov. George F. Allen declared, "We have discovered America's birthplace -- the original fort."
William Kelso, director of archaeology of the Association for the Preservation of Virginia Antiquities, which owns the site and supported the excavations, said in an interview that the artifacts should afford historians a clearer view of "a very early Colonial society" in the time of Queen Elizabeth I and her successor, James I.
Among the most interesting finds, Kelso said, were dozens of sky-blue glass beads apparently manufactured by the colony for trade with the Indians.
"John Smith got himself out of hot spots by trading these beads," he said.
The project, which is also supported by the National Geographic Society, is expected to excavate most of the site of the 1-acre fort and surrounding town ruins by the 400th anniversary of Jamestown, in 2007.
"Any time we get early Colonial artifacts, it's important," said James Axtell, a historian at the College of William and Mary in Williamsburg, Va.
"There's also the symbolic significance here," he said.
"Jamestown represents the founding of Virginia and of English America, even though other places are better examples of successful colonization."
Indeed, if John Rolfe, who married Pocahontas, had not developed a hybrid tobacco in 1613 that won a ready market in London and the first economic boost for the colony, historians say, Jamestown would have become just another Colonial failure.
An earlier English settlement, in 1584 at Roanoke Island, which is now part of North Carolina, was a disastrous failure.
In 1562, French Huguenots had no more luck with their Charlesfort, the site of which on the South Carolina coast was discovered earlier this year.
Three years later, in 1565, the Spanish founded St. Augustine in what is now Florida and which is the oldest permanent European settlement in North America outside Mexico.
Colonists paid for mistakes
Jamestown's early tribulations were many.
As Samuel Eliot Morison wrote in "The Oxford History of the American People," the colonists "made the usual mistake of first-comers in America by settling on a low, swampy island."
They also happened to put down among a mighty Indian confederacy, which made its first attack on the new fort on May 26, 1607.
So because of malaria, starvation and death at the hands of Indians, only 38 of the original 104 settlers lived through the first year.
High mortality and bad management led to rumblings of mutiny, which provoked harsh punishment.
Supply ships from England were few and inadequate; one relief ship became wrecked on Bermuda, an event that inspired Shakespeare's "The Tempest."
"It's incredible that the colony survived," said Axtell. "There was 80 percent mortality in the first 15 years.
"They had no way to make money in the first years. They were a poorly organized community and ill supplied.
"And their relations with the native people were probably the poorest of any place."
An account of the settlement written in 1610 described the original fort as triangular, with a 360-foot wall on the river side and the other two sides 300 feet long.
Two sides of the fort form a 46.5-degree angle, identical to the number given in the written account.
The palisades were made of vertical planks and posts of oak and walnut. From the new excavations, it now appears that only 20 percent of the original fort may have been lost to the river.