Hundreds of people spent WWII making chemical shells at the site
The only British ammunitions site to remain a secret during World War II could be declared an ancient monument.
The Rhydymywn Valley works, near Mold, Flintshire, produced hundreds of tonnes of mustard gas shells.
Its scientists were also sent to work on the Manhattan Project in the US, which built the first atomic bomb.
Cadw, which looks after historic sites for the Welsh Assembly Government, says it is considering whether parts of the plant should now be preserved.
Inspectors have visited the site and say some parts of the Valley works could be given full ancient monument status, while other parts could be made protected Grade II listed buildings.
From this little building came the genesis for the atomic bomb
Colin Barber, Rhydymwyn Valley historian
It would mean that Cadw must be consulted before any changes are made to the structures on the site by its current owners, the Department for Environment, Food and Rural Affairs (Defra).
Any parts declared ancient monuments would be taken over by Cadw, and maintained indefinitely for the public to visit.
"This would be fantastic news for Rhydymwyn Valley," said Colin Barber, who acts as the site's historian.
"This is a truly terrific site, with amazing stories to tell."
Cadw has identified what are known as the Pyro and Runcol buildings to be given Grade II listed status. They were both originally built to produce mustard gas, though only the Runcol building was ever used.
But in 1942, scientists began work in Pyro building six, on a secret project called "Tube Alloys", carrying out experiments to enrich radioactive uranium.
The expertise developed there was later called on when its researchers were sent to America to work with Robert Oppenheimer on the Manhattan Project, which built the world's first atomic bomb.
"From this little building came the genesis for the atomic bomb, nuclear submarines, and much of what the nuclear industry is today," said Mr Barber.
"We would love the opportunity to turn Pyro six into a museum so we let people know just what an important role it played in our history."
Cadw said the proposals are still at an early stage and it will be many months before the full plans for the site are finalised.
"When that is done, we will then consult the local authority and the Royal Commission and inform the site's owners, Defra," said a spokesman.