Title: London.
Question: What was London's estimated population at the time of the 2011 census?

Title: Comcast.
Question: What Pennsylvania cable provider did Comcast buy controlling interest in during 2005?

Title: John von Neumann.
Question: What caused a setback in naive set theory at the beginning of 20th century?

Title: Middle Ages.
Question:
What Italian city experienced a popular revolt?