You will be given a definition of a task first, then some input of the task.
Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.

Almost nothing is left of the Bastille except some remains of its stone foundation that were relocated to the side of the Boulevard Henri IV. Historians were critical of the Bastille in the early 19th century, and believe the fortress to have been a relatively well-administered institution, but deeply implicated in the system of French policing and political control during the 18th century.
Output:
What material was used for Bastille?