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It is customary to have stations in the centre of a city built very deep , not only to minimise disruption , but also , because of the Cold War threat , they were built to double as bomb shelters , and many old stations do feature provisions such as blast doors and air filters .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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