Albert Barnes Commentary 1 Kings 10:17

"And [he made] three hundred shields of beaten gold; three pounds of gold went to one shield: and the king put them in the house of the forest of Lebanon." — 1 Kings 10:17 (ASV)

These shields, along with the 500 David took from Hadadezer (2 Samuel 8:7), were hung around the outer walls of a building. This building was considered part of the “house of the Forest of Lebanon” but was separate from it. It was sometimes called “the Tower of David” (Song of Solomon 4:4) or, based on its use, “the armory” (Song of Solomon 4:4; Isaiah 22:8).

The practice of hanging shields on outer walls for ornamentation seems to have existed in Tyre (Ezekiel 27:10–11), Rome, Athens, and elsewhere. Traces of this custom are also thought to be found in Assyrian sculptures.