It was once the world’s largest building under one roof, built by the U.S. government in less than two years as part of a top-secret race to build the world’s first atomic bombs during World War II.

Officials say it also helped win the Cold War.

But five years after demolition started, the K-25 Building is gone. Officials, workers, and invited guests watched the last section of the giant building crash to the ground on Thursday.

The mile-long, U-shaped K-25 Building enriched uranium through a process called gaseous diffusion. It was the largest facility in the U.S. Department of Energy complex. Debris shipments are expected to be completed in the spring of 2014.

The $1.1 billion project is under budget and ahead of schedule. [Read more…]