In the fiction of J. R. R. Tolkien, Moria was the name given by the Eldar to what had once been an enormous underground complex in north-western Middle-earth, comprising a vast network of tunnels, chambers, mines and huge halls or 'mansions', that ran under and ultimately through the Misty Mountains. There, for many thousands of years, lived the Dwarf clan known as the Longbeards.
According to Tolkien's fiction, the city and one-time centre of dwarven industry was also called Hadhodrond by the Sindar, Casarrondo by the Noldor and Phurunargian in the Common Speech, all meaning the Dwarrowdelf. For over a thousand years of the Third Age it was widely known as Moria, meaning 'The Black Chasm' or 'The Black Pit'.
From Gundabad, Durin's growing clan "spread southward down the vales of Anduin", all the while "under attack from the orcs (sic) of Morgoth". According to legend, Durin ultimately found "a glen of shadows between two great arms of the mountains, above which three white peaks were shining". Within this heavily wooded valley, a long series of short water falls led down to a long, oval lake, which appeared to have a magical quality: "There, like jewels sunk in the deep shone glinting stars, though sunlight was in the sky above". Perceiving these stars as a crown glittering above his head, Durin took this as an auspicious sign, and named the lake Kheled-zarâm, the 'Mirrormere'.
The three peaks overshadowing the lake he named Baranzinbar 'the Redhorn', Zirakzigil 'the Silvertine' and Bundushathûr, 'Cloudyhead'. The icy cold springs feeding it he called 'Kibil-Nâla', of unknown meaning, although to the valley itself he gave the name 'Azanulbizar', The Dimrill Dale. Durin chose the caves above Kheled-zarâm as the earliest beginnings of his stronghold: Khazad-dûm, 'the Dwarrowdelf'.
All of these places became revered amongst Durin's people in later days. His descendants erected a rune-carved stone monolith at the site whereupon he had first looked into the Mirrormere, and although it had become indecipherably weatherworn by the end of the Third Age — broken, cracked and faded — the influence of Durin I, the founding king of Khazad-dûm, was never forgotten.
Khazad-dûm waxed continuously in size and population in Durin's long lifetime, until it became the "greatest of all the mansions of the Dwarves", even before the return of the Noldor to Middle-earth. By that time, Khazad-dûm was already "a name and a rumour from the words of the Dwarves of the Blue Mountains" to all the Eldar of Beleriand.
After his death, the reputation of Durin's realm continued to grow, not merely due to his spiritual ascendancy over the other Fathers of the Dwarves as the eldest amongst them, or the Dwarrowdelf's growing size, but to its great wealth, which was founded upon the uniquely precious metal mithril, which was universally prized yet found nowhere else in Middle-earth.
Khazad-dûm played no part in the wars of Beleriand, and in fact gained a respite from orc attacks throughout the last five centuries of the First Age, "when Morgoth needed all his strength" elsewhere. The Longbeards maintained contact with all the other six dwarf clans, and after early Men arrived in Rhovanion, Khazad-dûm quickly began trading with them, exchanging the products of their growing metallurgical and masonry skills for food, to the great profit of both peoples.
With the foundation of the Noldorin realm Eregion to the west of Khazad-dûm around the year 700, friendly relations between the Longbeards and the Elves became firmly established. Many of the Elves then became involved in the development of Khazad-dûm's mansions as a consequence, and it "became far more beautiful" during this period. This friendship also resulted in a massive subterranean extension westwards: the Dwarrowdelf's habitable parts remained in the eastward side, but passages were delved through miles of rock that terminated at a gigantic stone portal outside this elven realm — The West Gate — "which opened out into their country and was chiefly used by them." Celebrimbor, the Lord of Eregion, used mithril lettering on the dwarf Narvi's behalf when the latter built these, to create an inscription that read Im Narvi hain echant. Celebrimbor o Eregion teithant i thiw hin: "I, Narvi, made them. Celebrimbor of Hollin drew these signs."
The West Gate allowed the Elf lady Galadriel to pass eastwards through Khazad-dûm and establish Lothlórien beneath Azanulbizar, and the Nandorin elves that had earlier evacuated the area to escape Khazad-dûm's growing power, returned to settle there.
All of the Dwarrowdelf was originally illuminated by many "shining lamps of crystal", although the halls of the highest level were also lit with windows and shafts carved through the mountain sides. These levels lay between flights of fifty or more stone steps, with seven hollowed out of the mountains above ground level, and many more subterranean levels — or 'Deeps' — beneath the Great Gates at the head of the Dimrill Dale. Every level comprised a multitude of arched passages, chambers and many pillared halls, often with "black walls, polished and smooth as glass". Below the level of the Gates lay mines, treasuries and even dungeons, although far below the lowest Deep of Khazad-dûm, lay primordial tunnels in perpetual darkness, gnawed by 'nameless things' that had lived there since the earliest beginnings of Arda. Few if any actually ever glimpsed these creatures, and no description of them is extant.
One important feature of the Dwarrowdelf was the defensive structure known as Durin's Bridge, "a slender bridge of stone, without kerb or rail", that spanned a fifty feet wide chasm of indeterminate depth, allowing only one enemy soldier to cross. Another, steeped in legend, was The Endless Stair, which ascended "from the lowest dungeon to the highest peak", where it terminated within Durin's Tower, carved from the solid rock at the tip of Zirakzigil. The West Gate and the Great Gates remained the only two known exits from Khazad-dûm, however, which proved fortunate during the War of the Elves and Sauron in the middle of the Second Age: the Dark Lord's victorious host in Eregion was unexpectedly distracted by a powerful assault of dwarves from Khazad-dûm, who subsequently retreated behind Narvi's impregnable doors after their purpose was achieved. Afterwards, Sauron harboured deep hatred for Khazad-dûm and ordered his Orcs to trouble Durin's folk at every turn, even though "the halls of Khazad-dûm were too deep and strong and filled with a people too numerous and valiant for Sauron to conquer from without". Despite this, "its people began to dwindle" from this time, possibly due to the loss of foodstuffs that had been provided by Men in the vales of Anduin.
Many centuries later, in 2790, driven from Erebor by the dragon Smaug, Thrór, heir of Durin, foolishly attempted to re-enter his ancestral home despite warnings not to. He was slain by the Orc chieftain Azog, an infamous murder that precipitated The War of the Dwarves and Orcs culminating in a bloody battle outside Moria's eastern gates nine years later. The Dwarves were victorious and Azog himself was beheaded by Dáin II Ironfoot before the great orc could reach the safety of the gates, but the Dwarves had suffered great losses and remained unwilling to face Durin's Bane. Casualties were so high that the dwarves were unable to craft sufficient crypts for the slain, as was their wont, and were forced instead to burn their dead. The felling of trees to accomplish this was so great that the Valley of Azanulbizar (the "Dimrill Dale") was forever deforested. Those slain were honoured in future years with the appellation "Burned Dwarf". After this Pyrrhic victory, Thrór's son Thráin II attempted to re-enter the Mines, but Dáin stopped him and prophesied that some power other than the Dwarves must come before Durin's folk could return to Moria.
Towards the close of the Third Age a few generations later, the dwarf Balin led a company to reopen the city, including Flói, Óin, Ori, Frár, Lóni, and Náli, although Balin's mission was against King Dáin's wishes. At first all went well, but after five years the colony was destroyed by Orcs. King Dáin was then visited twice by a messenger from Mordor, offering to return the remaining three of the Seven dwarf rings and the realm of Moria, if Dáin would cooperate in finding the One Ring. The offer was refused, but it is not known whether Sauron "the base master of treachery", had any power over Durin's Bane.
The Fellowship reluctantly passed through Moria in 3019, and although the Great Gates lay shattered by this date, they passed beyond Narvi's doors in the west only with difficulty and in great peril. Many of the long deserted lower Deeps had become flooded and inaccessible, and the Fellowship were gambling that most of its Orcs had been killed in the Battle of Five Armies a few decades earlier. After reaching the Chamber of Mazarbul towards the end of their journey, the Fellowship were attacked there by a Troll and many Orcs, before being approached by Durin's Bane itself. Gandalf confronted the Balrog on the Bridge of Khazad-dûm, near the remains of the Eastern Gates, where the two duelled briefly before plunging together into the abyss beneath it, allowing the rest of the Fellowship to escape. Both Gandalf and the Balrog survived the fall to continue their epic duel from the primordial depths below Moria to the tip of Zirakzigil, ultimately demolishing both the tower and the top of the Stair.
With the death of the balrog, the way was at last clear for the Longbeards to reclaim the Dwarrowdelf however, and it is told that a few centuries into the Fourth Age, Durin VII - a descendant (some sources say the son) of Thorin III Stonehelm - at last led his people back to their longed-for ancient homeland early in the Fourth Age, retrieving what they could of Khazad-dûm's once-mighty riches.
The Doors of Durin, also called the West-door or the West-gate of Moria, were created in the Second Age by the Dwarf Narvi, as the western entrance to Khazad-dûm. In these times, they stood open and were guarded by a doorwarden, allowing free and friendly trade between the Elves and the Dwarves.
The doors were made of ithildin, which mirrored only starlight and moonlight. When the moon was out in full and ancient words long-forgotten were spoken, fine silver lines would appear, outlining the secret door. The designs on the arch, which were made by the Elf Celebrimbor, included a hammer and an anvil (the emblems of Durin); a crown and seven stars; two trees surmounted by crescent moons; and a single star (the Star of the House of Fëanor). The inscription at the top of the arch read: "Ennin Durin aran Moria. Pedo mellon a mino" - "The Doors of Durin, Lord of Moria. Speak, friend, and enter.""(More literally translated "Say friend and enter")
Merry gives the idea that the answer is in the riddle and Gandalf figures it out.
Shortly after Gandalf opened the doors, the Watcher in the Water attacked the Fellowship as they entered the Mines, ripping down the holly trees that flanked the doors and barricading the gate; the Watcher also piled rocks in front of the gates. In the film, the Watcher caused a cave-in instead, apparently destroying the gates, but this is not the case in the books.
The Dimrill Gate had two great doors that hung from tall doorposts. The doors bore messages in several languages inscribed in runes. In Khuzdul, the language of the Dwarves, there were spells of prohibition and exclusion. There were also warnings against entering without the permission of the King of Khazad-dûm written in Quenya, Sindarin, the Common Speech, and the languages of Rohan, Dale, and Dunland.
Gandalf entered Moria through the Dimrill Gate while searching for Thráin II who disappeared in 2845. Aragorn also passed through the Dimrill Gate during his journeys in Middle-earth.
Gollum entered the Dimrill Gate in August of 3018 and made his way through Moria to the West-gate. The Fellowship entered Moria through the West-gate on January 13, 3019, and journeyed eastward followed by Gollum. Gandalf confronted the Balrog on the Bridge of Khazad-dûm and fell into the abyss. Aragorn led the others out of Moria through the Dimrill Gate.
The Chamber of Mazarbul was a room in Moria containing the Tomb of Balin. It was located to the right of a pathway that branched off the north end of the Twenty-first hall. When the Fellowship found the chamber as they passed through Moria, Balin's tomb was located inside it, and a bright shaft of sunlight streamed in from outside the mountain to land directly on the tomb. There were two stone doors leading into the chamber. Many deep recesses were cut into the chamber rock containing chests that had been recently looted by the orcs inhabiting Moria. In one of these was found the Book of Mazarbul.The book told of Balin's expedition to Moria. The last words in the book were writen by Ori and he wrote. " We have barred the gates, but can not hold them for long. We can not get out. They have taken the Bridge and the Second Hall. Frar and Loni and Nali fell there. The pool is up to the wall at the Westgate. The Watcher in the water took Oin. We can not get out. The end comes. Drums, drums in the deep. They are coming." It was in the Chamber of Mazarbul that the Fellowship engaged in a brief fight with a band of Moria orcs and a cave troll and where Gandalf made his first stand against the Balrog.
The Chamber's depiction in Peter Jackson's The Lord of the Rings: The Fellowship of the Ring film is based on the description in the books; however the walls are covered with inscriptions in Khuzdul and the Common Speech (English) not found in Tolkien's work.
The Bridge of Khazad-dûm is a narrow stone bridge crossing a chasm within the eastern gates of Moria. It lends its name to Chapter 5 in Book II of The Lord of the Rings, in which Gandalf referred to it as Durin's Bridge. There Gandalf and the Balrog fight and destroy the bridge.
The bridge was built to guard the East Gate of Khazad-dûm. It narrowly spanned a deep chasm built under the high arches common in Khazad-dûm. This gave the bridge powerful defensive value, for if an enemy were to breach the East Gate of Khazad-dûm, he would be forced to cross the span of the Bridge (some fifty feet) in single file line, exposing him to the arrows of the Dwarven defenders.
The Eastern end of the bridge connected to the First Hall and through that toward the East Gate of Khazad-dûm. The Western end of the bridge connected to the superstructure of the main city itself.
In The Fellowship of the Ring, the first volume of The Lord of the Rings, the eponymous Fellowship were forced to seek a path through Moria, long since abandoned by Durin's Folk. Through the course of this journey, the Fellowship encountered Durin's Bane, a balrog that had survived the destruction of Thangorodrim.
Seeing that the Fellowship was over matched, Gandalf challenged the Balrog on the span of the Bridge of Khazad-dûm. In the course of this fight, Gandalf shattered the Bridge (and with it, his staff), allowing the rest of the Fellowship to flee through Moria by the Eastern Gate.
The Endless Stair rose from the lowest dungeon of Moria to Durin's Tower at the summit of Celebdil. The Endless Stair was of such legendary status among Dwarves that some considered that it had never existed, but Gandalf confirmed its existence to Gimli when he recounts his battle with Durin's Bane (a balrog). Durin's Tower and the top of the Stair were destroyed in that struggle. The height of the Stair is not known, but Gandalf said that it climbed many thousands of steps in an unbroken spiral.