The Royal Gunpowder Mills are a former industrial site in Waltham Abbey, England. It was one of three Royal Gunpowder Mills in the United Kingdom (the others being at Ballincollig and Faversham). Waltham Abbey is the only site to have survived virtually intact.
The Royal Gunpowder Mills, Waltham Abbey, were in operation for over 300 years. Starting in the mid-1850s the site became involved in the development of revolutionary nitro-based explosives and propellants known as "smokeless powder". The site grew in size, and black powder became less important.
Shortly after the Second World War it became solely a Defence Research Establishment – firstly the Explosives Research and Development Establishment, then the Propellants, Explosives and Rocket Motor Establishment Waltham Abbey; and finally the Royal Armament Research and Development Establishment Waltham Abbey.
The Mills are an Anchor Point of the European Route of Industrial Heritage, set in 175 acres (0.71 km2) of parkland and containing 21 buildings of major historical importance.