For archaeologists overseeing the massive dig at the World Trade Center site, it was a groundbreaking discovery.
A centuries-old ship was uncovered by workers excavating land at the WTC complex last July.
"We noticed a curved piece of timber that was dislodged by the backhoe and immediately thought, 'Oh my god, that looks like a piece of a ship,'" said AKRF archaeologist Molly McDonald.
It was evidence there was once zero ground… at Ground Zero.
"This entire excavation site originally would have been under the Hudson River," McDonald said.
"Occasionally ships are found because they sunk in the harbor or they were intentionally sunk as part of a landfill."
The ship was found sliced in half. Historians say it was most likely deemed un-seaworthy and used to supplement the man-made land at the WTC, which has been commonly referred to as “Ground Zero” ever since the September 11th attacks.
"The original shoreline, at the time when the first colonists got here was at Greenwich Street, at the left of the South Tower footprint," said AKRF archaeologist Elizabeth Meade.
The land was filled in little by little, creating all but a sliver of the original 16-acre World Trade Center site. Both of the Twin Tower footprints would be underwater if the shoreline still looked like it did when Manhattan was discovered in 1609.
Dutch settlers started building land out into the Hudson River, then known as the North River, in the 1680s.
But it wasn’t to make more space. It was to make more money.
"They were there from the beginning to make a buck, or a guilder," said Dr Sarah Henry, a historian from the Museum of the City of New York.
Traders from the Dutch West India Company controlled Manhattan real estate at the time. They noticed that when the river’s tide was out, sandy waterfront property appeared. So, they sold it.
"They call them water lots. It's the land that's sometimes underwater,” Henry said. “They begin to sell that and that's when the landfill begins."
The landfill was gradual. It started by building piers out into the river.
Those piers became streets. The slips of water between them became city blocks, by filling them with dirt from leveled hills, mixed in with large items (like ships deemed no longer sea-worthy) and a lot of garbage.
"Trash was very useful when you were making up land,” said AKRF archaeologist Diane Dallal.
“There were no laws regulating what you could throw into a landfill, so you could throw in anything. The neighbors always complained about how it smelled horrible."
Among the items archaeologists have recently found at the WTC site are animal bones, broken china plates and bowls, and leather shoes they believe came from “Cobbler’s Hill,” a once nearby area where shoes were made in the colonial era.
During America’s infancy, building out the port on Manhattan’s West Side was critical to importing items like china and exporting items like shoes.
"By increasing the commercial property at the waterfront they could just keep growing the economy, which was quickly becoming one of the most important in colonial America," Meade said.
The British proved to be as ambitious with land-filling as the Dutch. By 1776, the British had completed the land where the Twin Towers would eventually stand. But work stopped during the Revolutionary War.
“This is 1776. Not a lot is going to happen during the seveb years of the revolution because they're busy having a war,"Henry said.
The Americans picked up the project after gaining their independence.
By the 1840s, they fleshed out landfills all around the island using dirt and rock from the creation of the current New York City street grid.
“Most of the hills of Manhattan were obliterated in the process of putting the down the 1811 grid," Henry said. "The debris from the grading was used to enlarge the infrastructure of the entire shoreline."
That pushed the port on lower Manhattan's West Side into deeper water, making it an ideal harbor for bigger and bigger ships.
"New York is now not only the most important port in the United States," Henry said. "It is now on its way to becoming the most important port in the world."
For about a century, New York grew "up" instead of "out" as skyscrapers started rising across the city. Lower Manhattan grew both up and out when ground was broken for the Twin Towers in the 1960s.
Landfill from the foundation of the first World Trade Center was dug up and re-used to create the neighborhood Battery Park City. It was Manhattan’s last major expansion through landfill.
"That really brings the story of landfill full circle,” Henry said. “From early Dutch experiments, the British aspirations, the early American ambitions… the drastic transformation of the shoreline into an island that's considerably bigger than what they found in 1609."
The American ingenuity going into the building of the new World Trade Center, and the Twin Towers that once stood tall nearby, would not be possible without the early Americans who created the man-made land beneath them.
One World Trade Center, formerly called the Freedom Tower, will stand northwest of the Twin Tower footprints.
According to archaeologists and early maps, One World Trade Center will stand on land built shortly after America declared its independence in 1776.
The new tower will stand a symbolic 1776 feet tall.