2 Kings 11:16

And they laid hands on her; and she went by the way by the which the horses came into the king’s house: and there was she slain.

Cross-reference

2 Chronicles 23:15 gives the parallel account of Athaliah's execution at the horse gate, nearly identical wording.

Nehemiah 3:28 mentions the Horse Gate as a location where priests repaired the wall; this same gate was where Athaliah was killed.