When the shortlist was announced, just before the Games began in July, judges described the Olympic Stadium in Stratford as having "a spirit of fun".
They said the architects had "designed a space to create an amazing atmosphere, where every seat has a great view".
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The terror attack carried out by Khalid Masood at Westminster that left four people dead lasted less than two minutes say police.
Two knives were found at the scene in Islington, North London, and the suspects fled on foot before being arrested.
The family of the police officer who was murdered in the Westminster attack have thanked those who were with him 'in his last moments'.