We've been so busy with the titular Rings of Power, we had completely forgotten that Celebrimbor is more than just a forger of ominous jewelry.
In The Rings of Power season 2, episode 5, we even see the fruits of some of his labors – and it's an object that will be familiar to those who have witnessed the Fellowship's early travels in the Third Age.
Spoilers for The Rings of Power season 2 follow. You have been warned!
The Doors of Durin in Rings of Power
In a previous episode of The Rings of Power, a design for the Doors of Durin, the ornate threshold that would later be seen in The Fellowship of the Ring, could be seen behind Celebrimbor.
In the fifth episode, we see that design come to life as Celebrimbor invites the Dwarves to Eregion to bear witness to his new masterpiece, which is named after the current ruler of Khazad-dum.
"Behold, the Doors of Durin," Dwarf smith Narvi says to the assembled group of Dwarves and Elves. "The new west gate of our mountain. Unbreachable, visible only by moonlight, and guarded by a password known only to friends."
While Celebrimbor says it's a "night for Dwarves", conversation soon turns to Annatar and his desire to forge nine rings for Men. The Doors of Durin, it seems, won't be part of this story – not yet, anyway.
What are the Doors of Durin?
Forged out of the metal Ithildin by Celebrimbor and Narvi and used to guard Khazad-dum and the Mines of Moria, the Doors of Durin would later be seen as a near-impenetrable barrier between the one-time Dwarven kingdom and the rest of Middle-earth.
Of course, as The Rings of Power takes place in the Second Age on the Lord of the Rings timeline, we haven't quite got to that point. Right now, they are a gift and symbol of the continued unity between Dwarves and Elves – as shown by the two trees on its design, signifying the borders between Eregion and Khazad-dum.
Later, in The Fellowship of the Ring, Frodo, Gandalf, and the rest of the Fellowship attempt to enter through the Doors of Durin. After much pontificating (and despite only being able to see the doors in the moonlight), the password is spoken by Gandalf after solving the inscribed riddle. The answer? 'Mellon', the Elvish word for friend. Clever.
For more from The Rings of Power, check our our guides to some of the Prime Video show's most mysterious characters: Adar, Annatar, and The Stranger.
