Instructions: Write an inquisitive question about a specific text span in a given sentence such that the answer is not in the text.
Input: Sentence: Tens of thousands of people from across the nation gathered at the National Mall Saturday to commemorate the 50th anniversary of the March on Washington and to rally for what they believe is the unfinished business of the civil rights battle .<sep>Span: National Mall
Output:
What is the National Mall?