England's buildings are littered with blue plaques placed by English Heritage, commemorating the birthplaces of important people, famous architecture and so on. English Heretics put Black Plaques up to commemorate an entirely different kind of heritage:
The Black Plaque scheme was instigated in October 2003. Its purpose is to commemorate and draw public attention to historical figures in such diverse fields as sorcery, the Royal Art, left hand path occultism and witchcraft, as well as the mentally infirm: tortured poets, psychopaths and village idiots.
(via Oblink)