I want to know the answer to the following question:
Where was the decision made for this council?
All the background I'm provided with is that "Far from being a mere "stopgap" pope, to great excitement, John XXIII called for an ecumenical council fewer than ninety years after the First Vatican Council (Vatican I's predecessor, the Council of Trent, had been held in the 16th century).". Is that enough to answer the question?
Answer: no