Maps, apart from helping travellers, could also be powerful weapons. All maps in the Soviet Union carried deliberate errors to mislead mysterious Western spies with purposeful paranoia-driven deviations. There were no mistakes - deliberate or otherwise - in the Soviet cartographers' military maps of the West; the Maps of the 20th century exhibition in the British Library holds a 1980s map of Brighton as a possible nuclear strike target, describing every single dwelling, warehouse and workshop in minute detail.