Is "under" considered as a noun modifier to "box"?

Question

He keeps his money box under his bed.

Does the adverb "under" modify the head "box"?

Answer 1

"Under" doesn't really modify anything there. It's a preposition and not an adverb. It tells you about the spacial relationship that exists between "his money box" and "his bed". Namely, it tells you that his money box is located or can be found under his bed.