דברי הימים א, פרק י״א, פסוק ז׳

King David’s establishment of his capital in Jerusalem was a gradual process of physical growth and expansion. What began as a small, heavily protected area eventually transformed into a larger royal city. The primary approach among commentators is that David initially settled in a stronghold, a fortified tower or secure location that formed part of the city [רלב״ג, ביאור שטיינזלץ].

A careful look at the history reveals a subtle distinction between the built fortress and the surrounding natural landscape. While earlier records focus on the constructed stronghold where David first lived, the focus eventually shifts to the high mountain itself, Mount Zion, which offered natural strength and protection [מלבי״ם].

At first, David lived strictly within the confines of the built fortress, and this specific structure alone was known as the City of David. Over time, however, the space became too crowded. David expanded his residence outside the walls of the original fortress and onto the broader mountain. As a result of this expansion, the people themselves began applying the title "City of David" to Mount Zion and the newly constructed buildings surrounding the original stronghold. The name naturally spread, extending far beyond the borders of the initial fortress [מלבי״ם, ביאור שטיינזלץ].