**Note : This information comes from the HoMe series of books, which means that it is considered to be from J.R.R. Tolkien's earlier, unrevised writings. Therefore, this information cannot necessarily be considered canonical.**

The Warden of the Great Gate apparently watched over the Gate of Steel, the seventh gate of Gondolin.

The Gate was opened by striking on a bar, which made the fence ring like a harp, giving forth clear notes that ran from tower to tower. Then riders would issue from the towers, and from the north tower one rider came forth on a white horse – the Warden of the Great Gate.

This information comes from "The Fall of Gondolin" in BoLT 2.
Encyclopedia entry originally written by atalante_star