instruction:
Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
question:
I which European city will you find 'Dam Square'?
answer:
dam square


question:
Established in 1919, which is the world's oldest surviving airline?
answer:
airline


question:
Arlanda airport serves which European capital city?
answer:

stockholm arlanda airport