Question: What is the 2015 population of the city in which Silberturm was located. 
Sentence (from "Silberturm"): Silberturm (English: "Silver Tower" ), formerly known as Dresdner-Bank-Hochhaus and Jürgen-Ponto-Hochhaus, is a 32-storey, 166.3 m futurist skyscraper in the Bahnhofsviertel district of Frankfurt, Germany.
Relevant evidence: Yes