Instructions: Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
Input: Which London landmark was designed by Sir Christopher Wren to commemorate the Great Fire of London?
Output:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
christopher wren