For 10 points, name this country home to Queen Christina and Gustavus Adolphus, with capital Stockholm.
A ruler of this country founded the Arcadian Academy in Rome after being converted to Catholicism by Pope Alexander VII. That ruler of this country invited Hugo Grotius and René Descartes to come to it, and they both died in it. This country's golden age started after the death of its King Charles (*) XII and the Treaty of Nystad. A king of this country won the Battle of Breitenfeld but was killed by Albrecht von Wallenstein's troops at the Battle of Lützen. That king of this nation was known as the "Lion of the North" during the Thirty Years' War. For 10 points, name this country home to Queen Christina and Gustavus Adolphus, with capital Stockholm.
A ruler of this country founded the Arcadian Academy in Rome after being converted to Catholicism by Pope Alexander VII.
Kingdom of Sweden [or Konungariket Sverige]