Glowdon is a heavily irradiated piece of land located in what used to be southeastern britain, encompassing the area roughly between old-world locations Bristol and Canterbury, with London as it's epicenter.
Some old-world documents relate that a massive thermonuclear detonation leveled London and flooded the region with radioactive fallout. The hills at north and south form a valley of sorts, which is believed to have lessened the spread of the blast's energy as well as fallout to other areas of the country.
This detonation, which Nexus historians have taken to calling the "Glowdon Event" has rendered much of mainland Britain uninhabitable due to risk of radiation poisoning.
Few battlegrounders have ever seen Glowdon, much less explored it, but they report it being an ash-gray wasteland of debris for several square kilometers, which glows an eerie dull green during nighttime. Horrible mutated creatures have been sighted wandering through it's ruins and the surrounding area. The farther away from the center, skeletons of old buildings and monuments start becoming more common, dotting the area like funeral pires to a world long gone.