By Greg Argos

BETHLEHEM, Pa. (CBS) – A piece of U.S. history will soon come crumbling down this weekend. Crews broke ground on Bethlehem Steel’s headquarters in 1969, known as Martin Tower, and despite attempts over the years to redevelop the building, the efforts have failed.

On Sunday, the historic building will be imploded. In just a few hours, it will be a pile of rubble and only CBS3 has the exclusive final look.

“It was state-of-the-art and a beautiful building,” a construction worker said.

It was also the symbol of U.S. industrial might for decades, the world headquarters of the now defunct Bethlehem Steel Corporation.

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“Controlled demolition does not blow anything up,” a construction worker said. “The explosives that are used in this process actually cut the steel. They are used to burn the steel support. What they do is they cut the steel in order to allow gravity to pull the building down.”

The 331-foot, 21-story building – the tallest in Pennsylvania outside of Philadelphia and Pittsburgh – has sat empty for 12 years.

(Credit: CBS3)

It’s now a skeleton of its former glory.

Pieces of its ornate interior sit in storage, waiting to be displayed in a nearby museum.

Those who worked at the steel company’s headquarters in years past plan on watching the building’s final moments.

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“It was just a remarkable building,” Hank Barnette, a former employee and board member, said. “It was spacious. It was new. It was steel centered.”

“It was about four years to make this,” a construction worker said. “It’s been here for 50 years and in about 30 seconds, it’ll be reduced to a pile of rubble.”

The plan is for the building to come down around 7 a.m. Sunday, weather permitting.

A multi-use complex with housing, office space and retail space is expected to take its place.