In 2010, excavators at the World Trade Center site in New York unearthed something they had never expected to find beneath the old foundations of a skyscraper: An old wooden ship. Now, according to a report from National Geographic, scientists have discovered where the ship came from.

It turns out that the vessel uncovered at the World Trade Center is actually a ship that was used in the Revolutionary War era. More accurately, the ship was built in Philadelphia in about 1773, and constructed with the same wood that was used to build famous Revolutionary War-era buildings like Independence Hall.

How have scientists managed to formulate such exact estimates on where and when the boat came from? Through the help of tree rings, of course. Columbia University’s Edward Cook is a scientist who actually specializes in tree ring dating, and he has used his knowledge to link the wooden ship found beneath the WTC to a mass timber harvest in Philadelphia. The wood from that harvest was used not only to build Independence Hall, but numerous other Revolutionary-era structures and vessels.

Today, the sailboat-like ship seems like an absolute miracle. Back in the 18th century, though, experts think it was probably looked upon as junk. In fact, the study theorizes that the boat was discarded in a landfill on the banks of the Hudson River shortly after its maiden voyage, which helps explain how it came to be hidden beneath one of the largest buildings in New York.