You will be given a definition of a task first, then an example. Follow the example to solve a new instance of the task.
This task is about creating an unanswerable question based on a given passage. Construct a question that looks relevant to the given context but is unanswerable. Following are a few suggestions about how to create unanswerable questions:
(i) create questions which require satisfying a constraint that is not mentioned in the passage
(ii) create questions which require information beyond what is provided in the passage in order to answer
(iii) replace an existing entity, number, date mentioned in the passage with other entity, number, date and use it in the question
(iv) create a question which is answerable from the passage and then replace one or two words by their antonyms or insert/remove negation words to make it unanswerable.

Passage: In 1763, Spain traded Florida to the Kingdom of Great Britain for control of Havana, Cuba, which had been captured by the British during the Seven Years' War. It was part of a large expansion of British territory following the country's victory in the Seven Years' War. Almost the entire Spanish population left, taking along most of the remaining indigenous population to Cuba. The British soon constructed the King's Road connecting St. Augustine to Georgia. The road crossed the St. Johns River at a narrow point, which the Seminole called Wacca Pilatka and the British named "Cow Ford", both names ostensibly reflecting the fact that cattle were brought across the river there.
Solution: Who owned Cuba after the Eight Years War?
Why? This question appears to be relevant to the passage as both involves words such as 'Cuba' and 'War' which also exist in the passage. The passage mentions that "after the war, almost the entire Spanish population left, taking along most of the remaining indigenous population to Cuba". This information is not sufficient to conclude that which country owned cuba.

New input: Passage: The site where the Saint Petersburg Passage sprawls had been devoted to trade since the city's foundation in the early 18th century. It had been occupied by various shops and warehouses (Maly Gostiny Dvor, Schukin Dvor, Apraksin Dvor) until 1846, when Count Essen-Stenbock-Fermor acquired the grounds to build an elite shopping mall for the Russian nobility and wealthy bourgeoisie. Stenbock-Fermor conceived of the Passage as more than a mere shopping mall, but also as a cultural and social centre for the people of St Petersburg. The edifice contained coffee-houses, confectioneries, panorama installations, an anatomical museum, a wax museum, and even a small zoo, described by Dostoyevsky in his extravaganza "Crocodile, or Passage through the Passage". The concert hall became renowned as a setting for literary readings attended by the likes of Dostoevsky and Turgenev. Parenthetically, the Passage premises have long been associated with the entertainment industry and still remains home to the Komissarzhevskaya Theatre.
Solution:
When was Saint Petersburg demolished?