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From the mid-1970 s , a new open " single-vault " design was developed by local engineers and became very popular , not only in Saint Petersburg , but some other cities as well .
 location: Saint Petersburg
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:
 location: Saint Petersburg