A song.
This designation indicates that the Psalm was intended to be sung, reflecting its use in worship and liturgical settings. Songs in ancient Israel were a means of teaching theology, expressing communal identity, and reinforcing cultural values. The musical aspect underscores the joy and celebration associated with the themes of the Psalm.

He has founded His city on the holy mountains.
The "city" refers to Jerusalem, often called Zion, which holds a central place in biblical theology as the chosen dwelling place of God (Psalm 132:13-14). The "holy mountains" emphasize the city's divine selection and sanctity. Geographically, Jerusalem is situated on a series of hills, with Mount Zion being one of the most significant. This location is not only strategic but also symbolic of God's protection and presence. Theologically, the founding of the city on holy mountains signifies God's sovereign choice and the establishment of His kingdom on earth. This phrase also connects to prophecies about the New Jerusalem (Revelation 21:2), symbolizing the ultimate fulfillment of God's plan for His people. The mountains can be seen as types of Christ, representing strength, stability, and the place where God meets humanity.

• This heading reminds us that certain Levites—descendants of Korah—were set apart to lead temple worship (1 Chronicles 9:19; 2 Chronicles 20:19).

• Their family history is a testimony of grace. Though Korah perished for rebellion (Numbers 16:31-33), his offspring were preserved (Numbers 26:11) and later served in the house of the LORD.

• By attaching their name to the psalm, the writers humbly acknowledge that God redeems and re-commissions even the line of a fallen ancestor—proof that His mercy endures forever (Psalm 103:17).

• This backdrop prepares us to hear the psalm as worship led by servants who know firsthand the seriousness of sin and the wonder of forgiveness (Psalm 42:4; 84:1-2).

• The label signals a piece designed to be sung, not merely recited. Melody helps truth settle into the heart (Colossians 3:16).

• Calling it a “song” underscores joy. The psalm that follows celebrates Zion’s glory and God’s global plan; naturally it bursts into music.

• By preserving the musical notation, Scripture reminds today’s believers that worship is both doctrinal and doxological—truth married to delight (Psalm 33:1-3).

• The declarative “He has founded” points to God Himself as the architect of Zion. Jerusalem exists by divine appointment, not human ingenuity (2 Samuel 5:7; Psalm 48:8).

• “His city” identifies Zion as uniquely belonging to the LORD. Of all places, He chose that ridge of hills to set His Name (Psalm 132:13-14; 2 Chronicles 6:6).

• “On the holy mountains” highlights separation and stability:

‑ Mountains convey permanence (Psalm 125:1-2), portraying God’s unshakable covenant with His people (Isaiah 54:10).

‑ “Holy” marks the site as set apart for God’s presence (Exodus 3:5). Holiness is not merely moral purity but distinctiveness—God dwelling with men.

• The statement also anticipates a broader fulfillment. Hebrews 12:22 speaks of “Mount Zion…the heavenly Jerusalem,” and Revelation 21:2 shows the city’s ultimate unveiling. The earthly Zion foreshadows the eternal dwelling God is preparing for all who are in Christ (Ephesians 2:19-22).

• Because the foundation is the LORD’s doing, assurance flows to every believer. What God establishes, no power can overturn (Psalm 46:4-5; Isaiah 28:16).

Psalm 87:1 anchors hope in the God who sovereignly chose, founded, and sanctified Zion. Authored by redeemed Levites, sung with joy, and declaring the LORD’s immovable groundwork, the verse assures us that God’s plans for His city—and for all who trust in Him—stand firm forever.

His foundation on the holy hill

Loveth Jehovah, (even) Zion's gates,

More than all Jacob's dwellings.

Here His foundation is equivalent to that which He hath founded, and the gates are put by metonymy for the city itself. (Comp. Jeremiah 14:2.)

With regard to the plural, mountains, it is probably only poetical, though geographically it is correct to speak of Jerusalem as situated on hills. Dean Stanley speaks of "the multiplicity of the eminences" which the city "shares, though in a smaller compass, with Rome and Constantinople" (Sinai and Palestine, p. 177).

(1) She is built upon the holy mountains;

(2) God loves her pre-eminently; and

(3) a glorious future is assigned to her in the counsels of God. Ver. 1. - His foundation is in the holy mountains. God's foundation - the city which he has founded - is "in the holy mountains;" i.e. in the hill country of Judaea, a congeries of mountains, "holy," since they surround the holy city and belong to the "holy land" (Zechariah 2:12).

Parallel Commentaries ...