The twisted metal part, jammed in a sliver of open space between the buildings, has cables and levers on it and is about 3 feet wide and 1.5 feet deep. It includes a clearly visible Boeing Co. identification number, New York Police Department spokesman Paul Browne said Friday.
"The odds of this being wedged between there is amazing," Browne said, adding it was not surprising that it went undiscovered for more than a decade given the location. "It had to have fallen just the right way to make it into that space."
Other World Trade Center wreckage had been discovered at the buildings and around the area in years past.
The piece of equipment was discovered Wednesday by surveyors inspecting the lower Manhattan site of a planned Islamic community center, at 51 Park Place, on behalf of the building's owner, police said.
An inspector was on the roof and noticed the debris and then called 911. Police secured the scene, documenting it with photos.
Police detectives and National Transportation Safety Board investigators will determine whether the equipment is from the American Airlines plane or the United Airlines plane that slammed into the twin towers on Sept. 11, 2001, destroying the towers and killing nearly 3,000 people.
When plans for the Islamic center, about three blocks from ground zero, were made public in 2010, opponents said they didn't want a mosque so close to where Islamic extremists attacked. They argued the site was "sacred" because landing gear from one of the hijacked Boeing 767 jets had punctured the roof of the building on Sept. 11.
During street protests, they clashed with supporters of the center, who said it would promote harmony between Muslims and followers of other faiths.
The building includes a Muslim prayer space that has been open for three years. After protests died down, the center hosted its first exhibit last year. The space remains under renovation.
Donna Marsh O'Connor, who lost her daughter Vanessa Lang Langer in the attacks and is a member of September 11th Families for a Peaceful Tomorrow, called the landing gear discovery "bizarre."
O'Connor is a supporter of the Islamic center and said the fact that the plane fragment was found there "makes me think that this was the right place for a center that was going to heal the divide."
In a statement, Sharif El-Gamal, the president of Soho Properties, which owns 51 Park Place, said workers called the city and the police as soon as they discovered the landing gear. He said the company is cooperating with the city and the police to make sure the piece of equipment "is removed with care as quickly and effectively as possible."
The medical examiner's office will complete a health and safety evaluation to determine whether to sift the soil around the buildings for possible human remains, police said.
Patricia Riley, whose sister Lorraine Riley was killed in the Sept. 11 attacks, called the landing gear discovery "very strange."
"Twelve years later we are still finding remnants of the attack on our country," she said. "... For years to come we'll continue to find things that we didn't see before. Hopefully they'll serve as a reminder that we have to stay vigilant."
Outside the Islamic center building, known as Park51, a police officer stood next to the door on Friday and a police barricade was set up to contain the many journalists who had gathered to try to see the piece of the plane.
The landing gear could not be seen from the sidewalk so commuters rushed by and looked quizzically at the gathering.
Among the bystanders was one immersed in the legacy of the attacks: Van Vanable, heading home from his job as an ironworker building the new 1 World Trade Center.
"Amazing," he said of the find. "There's still pieces to the puzzle."
The Park51 space, a former Burlington Coat factory, is a five-story, mildly run-down building. Renovations are expected to take years and would add an auditorium, a pool, a restaurant and culinary school, a child care facility and artist studios.
The piece of plane is wedged in an alley space between that building and 50 Murray St., a luxury loft rental building.
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