In an official report The Royal Gunpowder Mills Waltham Abbey were described as "the most important site for the history of explosives in Europe." Many of the major world advances in gunpowder and explosive production using a range of technologies were made here, continuing into the later role of Research Centre, extending to rocket propellant. The listed buildings are unique surviving structures spanning the range of this activity which was carried on for the Crown in conditions of secrecy for over 200 years. This came to an end in 1991 when the Establishment's role was transferred to other centres and from 2001 for the first time this remarkable site was opened to the outside world.