The final pieces of major structural steel were installed this month for the largest building at the Madison County plant that will destroy chemical weapons at Blue Grass Army Depot.

The Munitions Demilitarization Building has 143,000 square feet and more than 3,650 tons of structural steel, said Assembled Chemical Weapons Alternatives, the Department of Defense agency overseeing the plant's construction.

The building, which has a footprint the size of about two adjacent football fields, is the largest and most complex facility at the plant under construction. The building will contain the automated process to disassemble chemical weapons.

Construction of the plant is more than 64 percent complete.