The K-25 uranium enrichment plant in Oak Ridge played a vital part in the Manhattan Project during World War II. Now, 70 years later, that complex is almost completely demolished.
"Today is a very significant day," said current demolition contractor UCOR president, Leo Sain, shortly after one of the final buildings, the "north tower" was leveled.
"We had a lot of work inside the building, such as removal of waste we had to get out before we could demo," Sain added.
Since K-25 stopped uranium production, it has been a long, and expensive process to clear up the site from contamination.
Department of Energy officials said it costs $1.1 billion for the 20 year total demolition process. In a 2012 10News Investigation, the D.O.E. thought it would cost $460 million to tear down K-25 and its sister facility, K-27. The D.O.E. has updated that bottom line throughout the process.
From switching contractors and being behind schedule at one point, one of the last buildings in this complex is now just a memory as of Wednesday morning.
"It's a huge achievement in the progress of clearing up the site, and at the same time, (shows) what the men and women did, the men and women who helped build that building," Mark Whitney with the Department of Energy said.
With only a few buildings left standing on the complex, the future of the complex is still in question.
"We're also able to commemorate the K25 building and reach an agreement in the last year to preserve the history of that," said Whitney.
The Department of Energy wants to turn the land into an historic park, showing the equipment used to make uranium and how it helped in American weaponry. Whitney said Congress still hasn't approved the "historic park" status -- but leaders say it looks promising.
"We want to preserve the footprint of K-25," said Whitney. "We're doing several things that would allow future generations to remember what happened here and remember the great work the men and women here did."
The "tech area," on the south end of the complex still has five buildings that need to be demolished. Workers are clearing it from contamination, and it should be leveled by 2015.
Still, the north tower is one big step closer to the future of the site.
"What (K-25) has done to support the country over the years is huge," said worker Sain.