Old Testament Jerusalem was the capital city of God's people in ancient times. As such, it served as the center of government, religion, culture, business, learning, arts, international trade, tourism, and diplomacy, etc. And it also served as a foreshadow of the greater, New Testament capital City of God's people today, "the Heavenly Jerusalem."
In Bible times, a reference to "Jerusalem" was like saying "Washington D.C." today, a quick reference to Government.
But it was also like saying "Vatican City" (religion)
Or like saying "New York" (business)
Or "London" (international finance)
Or "Geneva" or "Brussels" (international diplomacy)
Or "Paris" (arts)
Or "Silicon Valley" (technology)
So when the New Testament makes mention of "the Heavenly Jerusalem" it is like saying "the Heavenly Washington D.C." that is, it is understood as being the seat of "the Government from Heaven (Sky)." But it is also like saying, "the center of religion, culture, business, etc. from Heaven (Sky)".
When we also understand also that "the Heavenly Jerusalem" is a metaphor for the universe of all Christians everywhere, we then understand that the global Christian Community is ordained by the Word of God to be the capital City of all things, the center for religion, civil government, business, learning, arts, culture, etc.
Just as Jerusalem was the capital of Israel and Israel was the Lord's Inheritance, the Heavenly Jerusalem is the capital of the World since the ends of the Earth have become the inheritance of the Lord Jesus Christ, (Psalm 2). It can even be shown that the Heavenly Jerusalem, (the Church, the universe-wide Christian Community), is indeed the capital City over all Creation (all the Cosmos of Heaven and Earth).