DISCLAIMER: The locations are Tolkien's, as is Maglor, but what has happened to them is my own invention.
Civilisation
Ghardl and the Marshes of Arnor were far behind, and Maglor was descending the eastern side of the Pass of Caradhras – still extant, though now known as the Great Gate – before the next unexpected thing happened. The clouds which had masked his view of what had once been the Dimril Dale suddenly cleared, and he could see clear down to the sight of Lothlórien. What he could see, however, astonished him.
A great city stood where the Golden Wood had once grown, its suburbs sprawling halfway to the Dimril Dale itself, its centre straddling the confluence of the Anduin and the Celebrant. Maglor was stunned. His plans had involved travelling to Cerin Amroth, or perhaps to Caras Galadhon itself, but clearly his opinions of his cousin Artanis' power had been too high. He had assumed the site would still be held sacred, and would consequentially be avoided. Apparently, he had been wrong.
As an elf, Maglor could not have possibly understood the human habit of building on sites of power, rather than revering them. The Eldar could sense such power for what it truly was, but the Atani merely saw a place where strange things happened, and tried to contain it. If he had travelled further, he would have discovered cities at Rivendell, Isengard, Ithilien, and even the site of Barad-Dûr itself, humans having no way to distinguish between the powers of Good and Evil. But he did not know this, and only saw a great mass of humanity keeping him from his goal.
Incensed, the son of Fëanor strode down the Dimril Stair, prepared, if need be, to go to the ruler of the city and demand that they leave the site immediately, under pain of death. Whether he would have succeeded was not to be discovered however, for as he passed the lower end of the Mirrormere a great burst of power struck his mind from the west, and he halted. Turning slowly on one leg, he followed the path of the power . . . and found himself facing the site of the East-gate of Khazad-Dûm, the great Dwarrowdelf.
Of course, he thought, it was obvious. Seeing the fading of their realm, and predicting the influx of Men that would, sooner or later, occur, the Elves of Lórien would have taken whatever power remained and secured their legacy in the Mines. Perhaps it had been specifically arranged to signal any passing Elf, or perhaps he had merely been lucky. Either way, he knew now where he had to go.
Swiftly ascending the rocky slope that had once been a stair, Maglor came to the rock face that hid the Gate. Muttering the words of power that would reveal the doors, he frowned. The strength of these gates was greatly weakened, and if he had come but a few hundred years later, he might not have been able to open them at all. But he had come in time. Saying aloud the simple word that signalled his wish to enter – 'Mellon', as with the West-gate – he stepped back as the stone of the Doors cracked, pushing aside grass and stone alike to reveal the dark interior.
Stepping into the cavernous First Hall, he squinted into the gloom. The windows that had once lit it had long been filled, pouring stone and earth into the hall. Nevertheless, his eyes began to make out shapes, and he saw that, despite the age of the Mines, some of the pillars at least still stood.
The corridor at the far end was blocked, leaving access to the rest of the mines impossible, but Maglor saw that he did not need to go any further. What he had taken for pillars were not stone, but wood. Great mellyrn, still standing after thousands of years, preserved in a timeless moment by a Working such as that Yavanna had laid on all the plants of Middle-earth in the time after the Fall of the Lamps. Lothlórien's legacy – and the conclusion of Maglor's plan – remained. Moving swiftly to the nearest tree, the last son of Fëanor began to sketch in his mind the boat that would take word of his fate home.
The distance between Moria and Lórien may have been contracted slightly, but I've tried to make it believable. Judge for yourself.
Cloaked Eagle