Given the task definition and input, reply with output. 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 1529, Warsaw for the first time became the seat of the General Sejm, permanent from 1569. In 1573 the city gave its name to the Warsaw Confederation, formally establishing religious freedom in the PolishLithuanian Commonwealth. Due to its central location between the Commonwealth's capitals of Krakow and Vilnius, Warsaw became the capital of the Commonwealth and the Crown of the Kingdom of Poland when King Sigismund III Vasa moved his court from Krakow to Warsaw in 1596. In the following years the town expanded towards the suburbs. Several private independent districts were established, the property of aristocrats and the gentry, which were ruled by their own laws. Three times between 16551658 the city was under siege and three times it was taken and pillaged by the Swedish, Brandenburgian and Transylvanian forces.
When did General Sejm make Vilnius its permanent seat?