From “The Lord of the Rings: The Making of the Movie Trilogy”, by Brian Sibley, Houghton Mifflin 2002.
Chap. 3, ‘Setting the Scene.’ Talking with Alan Lee:
A sketch of Moria in the glory days before its ruination by Orcs leads to several hundred more, tracing the Fellowship’s journey from Moria Gate via Balin’s Tomb and the great hall of Dwarrowdelf to the Bridge of Khazad-dum.
“For Moria,” Alan tells me, “we wanted to evoke a feeling of somewhere that, while having been hacked from the mountain’s roots, was sophisticated and refined. The inspiration came from the straight lines of Dwarvish runes and gave a look that was geometric and crystalline.”
There are several plans mapping the different areas in the mines and an elaborate (and unused) suite of sketches showing the convoluted route – involving supports, walkways, planks and a bucket on a rope – by which Gollum may have tracked the Fellowship through the mines.
A vast amount of thought went into creating settings for the journey through Moria, a pivotal sequence in The Fellowship of the Ring. Alan speculates, for example, on the enormous size of the Dwarrowdelf chamber: “There is no logical reason for the pillars to be so tall or, indeed, for anything in Moria to have been built on such a large scale, and yet it doesn’t feel odd, suggesting as it does the scale of the Dwarves’ craft and imagination.” (p. 50)