In Psalm 48 the sons of Korah (who were responsible for choral and instrumental music in the temple) divulge some interesting facts about the City called Zion—otherwise known as the City of David (see 2 Samuel 5:7).
They sing, ‘beautiful in elevation...is Mount Zion on the sides of the north’ (which simply means on or near the northern borders (the Hebrew word YEREKAH means flank, side, edge or border and is so translated in Genesis 49:13 and other places). Judah’s northern boundary ran east to west just north of ancient Jebus (which became the City of David).
Their song continues to describe it as ‘the City of the great King’ and then says ‘God is in her palaces’ (plural). It goes on to tell of Gentile kings passing by, seeing it, marvelling and being troubled and fearful. Verse 8 speaks of the City as the City of God and verse 9 of thoughts of God’s lovingkindness within His temple.
Then notice verses 12 to 14 where the singers imagine a ‘walk about Zion’ to consider her strength...’consider her palaces' (again plural).
So, why ‘palaces’ in the plural? Because Zion, the City of David was the dwelling place of both their earthly and heavenly kings! The house or ‘palace’ of David is referenced in 2 Samuel 5:11 and it was built by Hiram, king of Tyre. Later, it was Solomon who built the ‘palace’ of the great King, the temple—also in the City of David. It is of both these palaces that the Korahites sang in the days of Solomon and later. (My view is that it is in that time because the sovereigns of the earth came to behold what he had built and to hear his wisdom—eg, 2 Chronicles 9:1-12 & 22-28).