The Gate of Steel was overlooked by two steel towers, one on either side of the pass before it opened onto the plain of Tumladen beyond. Between the towers ran the gate itself, composed of seven steel pillars, each rising to a spike, with the middle pillar surmounted by an image of the King-helm of Turgon. Between each pillar were seven lesser vertical steel rods, each tipped with a spearhead, while seven further steel rods ran horizontally across the structure.
Like the other Gates of Gondolin, the Gate of Steel had its own guards, led by the Warden of the Great Gate, a duty held for a time by Ecthelion of the Fountain. This Warden was armoured in silver, with a spiked helm tipped with a diamond, and a shield encrusted with crystals. For those few who passed through the Orfalch Echor as far as the Gate of Steel, this Warden had the power to allow them to pass onward to Gondolin itself, but once the Gate of Steel was passed, none were permitted to return that way.
The Gate of Steel would open for its Warden at a simple touch, which would cause it to glow with light before dividing and opening inward into the ravine. When a traveller passed the Great Gate, a signal went up: trumpets were blown in the towers of the gate, and were answered by trumpets from the Hidden City. So those rare travellers who made the journey to the Gate of Steel would pass through onto the plain of Tumladen and toward the secret city of Gondolin.
Notes
1
The Gate of Steel is specifically said to have been raised after the Nirnaeth, which was fought in I 472, centuries after the founding of Gondolin. This might be taken to imply that there had previously been only six gates, but all references to the gates throughout the history of Gondolin give the number as seven. The implication seems to be that Maeglin'sGate of Steel replaced a former gate that had guarded the inner end of the Orfalch Echor. If such an earlier version of the Seventh Gate did exist, it is nowhere described.