LONDON — A steel beam that once supported the south tower of the World Trade Center now sits on top of a small hill in London’s Queen Elizabeth Olympic Park, part of the metal polished to high shine by American artist Miya Ando .

The beam’s journey to London began in 2009, when Peter Rosengard, director of insurance, read that pieces of structural steel salvaged from the World Trade Center were in an aircraft hangar outside the John F. Kennedy International Airport. The New York and New Jersey Port Authority said it will consider requests from interested cities to permanently display parts of the buildings as monuments or public displays.

Some 67 Britons died in the September 11 attacks. Less than four years later, on July 7, 2005, four terrorists killed 52 people in a series of coordinated suicide bombings in London.

“I just knew I had to buy a piece of steel for London, and right away,” Mr Rosengard said.

He won the support of Boris Johnson, then mayor of London, and called the Port Authority to ask for a piece of steel for the capital. An employee of the Port Authority quickly told him to join the back of the queue: thousands of cities had already applied before him.

“I called him every day, I drove him crazy,” Mr. Rosengard said. After weeks of nothing succeeding, he hopped in a cab and called the port authority again on his way to Heathrow Airport. “I told them, ‘I’ll be at Hangar 17 tomorrow at 10 am,’ he said. He was admitted and allowed to choose the piece that in 2011 would end up in London.

The arrival of the steel coincided with the training by Mr. Rosengard of Since 9/11, an educational charity that teaches the events, causes and consequences of the 2001 attacks to British schoolchildren. It aims to prevent future generations from being drawn to extremism.

Mr Rosengard told the story of the four-ton tangle of metal on Saturday, hours before a commemorative event commemorating the events of September 11 began in Olympic Park. As he spoke, a man wearing a New York City Fire Department t-shirt approached the artwork and placed a small bunch of sunflowers at its base. The man looked up at the steel looming against the east London skyline, then firmly supported the ground.