Most of us have an idea of what the twisted wreckage of the World Trade Center looks like. We’ve seen it countless times in photos and on television over the past 10 years.

But not many of us have laid our hands on it.

The National Museum of the Marine Corps has a piece of World Trade Center wreckage—a steel I–beam, about 10 feet long, with two rows of bolts along the top. Some concrete and rebar remain attached to the edge, suggesting the support it once gave to a floor or a wall or the souls who lived their lives inside its frame.

The beam is sufficiently twisted and scarred, a reminder of what happened to so many lives on Sept. 11, 2001.

And the museum near Quantico encourages people to touch it. The act is surprisingly reciprocal considering its inanimate nature. It is a massive piece with a weight that exceeds the bounds of the physical world.

New York City fire department Battalion Chief Joseph Downey explained why in a dedication ceremony Wednesday.

“Our firefighters climbed this steel,” he said. “I spent nine months climbing on it, looking for my dad.”

Pieces of the wreckage have been memorialized across the country and around the world. Twisted metal from the twin towers sit in public parks and form the structure of memorials and works of art. More than seven tons of steel from the World Trade Center was used to form the bow of the USS New York, a Navy amphibious assault ship.

This I–beam is the centerpiece of a new exhibit that will officially open Thursday at the Marine Corps museum. It sits alongside a piece of stone recovered from the Pentagon after it was hit by a plane on 9/11.

But it was Downey and the memory of his father that explained the significance of the steel beam.

It is symbolic because of people such as Deputy Chief Raymond Downey, a retired Marine and a 39-year veteran of the New York City fire department.

He died along with hundreds of his fellow firefighters when the north tower fell.