Doors of Night
Ando Lómen ( The Door of Timeless Night ) From Quenya : Ando = Gate or door. Lómë = Shadow, gloom, night.
Moritanon. ( Former name Móritar )
Tarn Fui. ( Former name Tarna Fui )
In the Ambarkanta the Doors were made when Melkor was overcome and trusted into the Night but in all other accounts Melkor was trusted out beyond the Walls and Eärendil set as guard on the Door ( as if it was already there ) Thus the exact time and year of the making is impossible to find but in both cases they seems made in the time just before or at Melkor`s out-trusting in the aftermath of the War of Wrath.
1 Age.
F.A.597. The Doors of Night were set in the West of the Walls of Night and opens upon Kúma which is the Void, the Night without form or time. This was indeed perhaps one of the mightiest work of the Valar together with the Gates of Morning. There it still stands, utterly black and huge against the Walls. Its pillar and its lintel are of the mightiest basalt and great dragons carved in black stone with shadowy smoke pouring out from their jaws guards it.
The doors are unbreakable and it opens for a secret magic word alone who only Manwë and Arien knows and none but the Valar know how it was made for it is the last secret of the Valar. None can pass the Void save the Valar only and Eärendil guards the Doors and the ramparts of the world.
Related Links.: Battles.: War of Wrath.