Call to save WWII weapons plant (UK)
The Valley Works at Rhydymwyn, near Mold, Flintshire, produced hundreds of tons of mustard gas in World War Two.
But its history goes back to the 18th Century, according to university researchers who studied the site, now a nature reserve, for five months.
They are to present their findings at a public meeting on Tuesday.
Experts from Birmingham University's school of archaeology were commissioned to examine the industrial heritage at the Flintshire site.