Let's say you are to represent the "Ring of Doom"
Here's how to make your representation reasonably close to the ideal:
First, Look up every quote you can find a about it, starting with online wikis and libraries:
Tolkien Gateway:"Ring of Doom" gives:
Máhanaxar also called Rithil-Anamo was the Ring of Doom outside the golden western gates of the city of the Valar. Here the Powers gathered to hold their great councils, bathed in the light of the Two Trees while those Trees still stood, and here some of the most momentous decisions of Eä's history were made. It contains the word Máhan "chief Vala", derived from Valarin Mâchananaškad.
Tracing Mâchananaškad's link gives the Valarin word mâchan "authority, authoritative decision" and *(a)naškad as "ring" whence Black Speech nazg "ring", whence "Nazgul" [Ring-wraith]. A little more work is needed for "Rithil-Anamo" since the link is circular, but you can find risil (or riþil or rithil) "ring" + anamo "of doom" "juridical decision" or "(legal) justice", from nam- "to judge" whence "Námo" [Judge])
Other favorite sites, Encyclopedia of Arda and Lord of the Rings Wiki add a bit more:
Within the circles of the Máhanaxar were the thrones of the Valar and where they pronounced their judgments. Here the great villian Melkor was judged and sentenced for his evils. It was also where the great Ñoldorin elf Fëanor was judged for his deeds in Tirion and where he spoke to the Valar of his intentions, after the killing of his father at the hands of Melkor.
While searching Mahanaxar, you find the image above image by Jacek Kopalski showing tall stone chairs, each with an elvish letter. A central globe shines under the starlight sky. There are eleven lines in the floor, six going to the visible chairs with their gauzy occupants. This suggests eleven chairs. There are Eight Aratar, or 14 Vala that JRRT named that should be there. I cannot justify eleven. No sign of a green mound. No sign of light from Trees. This is a lovely rendering, but not fitting for what we know already.
RULE: Read the actual Tolkien for yourself.
And I got ahead of myself... "Green Mound". From The Silmarillion, Chapter One:
And when Valinor was full-wrought and the mansions of the Valar were established, in the midst of the plain beyond the mountains they built their city, Valmar of many bells. Before its western gate there was a green mound, Ezellohar, that is named also Corollairë; and Yavanna hallowed it, and she sat there long upon the green grass and sang a song of power, in which was set all her thought of things that grow in the earth. But Nienna thought in silence, and watered the mould with tears. In that time the Valar were gathered together to hear the song of Yavanna, and they sat silent upon their thrones of council in the Máhanaxar, the Ring of Doom near to the golden gates of Valmar, and Yavanna Kementári sang before them and they watched.
A lovely description of the Two Trees follows. Well skip over that, other than to note that the Two Trees are very nearby. We're working on the Ring of Doom.
Rule: Look up the word-parts of all Tolkien elvish.
- Ezellohar (Quenya [eˈzelːoxar] from Valarin Ezellôchâr) "the Green Mound". From ezello "green" + ?har (Quenya -sar from Valarin -har)(1)"stone" (2) "hard" (3) "trusted".
- Corollairë (Quenya[ˌkorolˈlaɪre]) Green Mound where the Two Trees of Valinor grew. Also called Coron Oiolairë ("Koron"), place-name: the "Mound of Eversummer" where the Two Trees grew. Contracted to Corollairë and Corlairë; or spelt with an initial k. From coron (1) "mound" (2) ("Koron"") "globe, ball" + oio 1) "an endless period" 2) "ever" + lairë (1) "summer" (2) "poem" (3) "meadow".
My Quenya Wordlist writes that it's doubtful lairë word carries three meanings, doubting "meadow" as ligitmate. Helge K. Fauskanger also includes some Valarin entries in his Ardalambion (Arda Languages) site
- mâchanâz, pl. mâchanumâz "Authorities", used of the greatest Valar, called Aratar in Quenya. The Valarin word was also adapted to Quenya as Máhan pl. Máhani.
- machallâm properly one of the seats of the Valar in the Ring of Doom, the source of Quenya mahalma "throne" (WJ:399, cf. UT:305, 317
- mâchan "authority, authoritative decision" (WJ:399). The source of Quenya Máhan, one of the eight chiefs of the Valar, though the translation Aratar was more usual. It is an element in Mâchananaškad "Doom-ring", Ring of Doom, adapted to Quenya as Máhanaxar or translated as Rithil-Anamo. (WJ:401)
All this points out that the thrones in the ring are for the Eight Aratar: Aratar ('The Exalted'; arat "high",+ -r = plural). These are named in the Valaquenta:
Nine were of chief power and reverence; but one is removed from their number, and Eight remain, the Aratar, the High Ones of Arda: Manwë and Varda, Ulmo, Yavanna and Aulë, Mandos, Nienna, and Oromë. Though Manwë is their King and holds their allegiance under Eru, in majesty they are peers, surpassing beyond compare all others, whether of the Valar and the Maiar, or of any other order that Ilúvatar has sent into Eä.
In "The Silmarillion" chapter 9, when the Two Trees are extinguished, we learn the area around the Circle is very large:
After a time a great concourse gathered about the Ring of Doom; and the Valar sat in shadow, for it was night. But the stars of Varda now glimmered overhead, and the air was clear; for the winds of Manwë has driven away the vapours of death and rolled back the shadows of the sea. Then Yavanna arose and stood upon Ezellohar, the Green Mound, but it was bare now and black; and she laid her hands upon the Trees, but they were dead and dark, and each branch that she touched broke and fell lifeless at her feet. Then many voices were lifted in lamentation;
Further searching for our keywords, "Ring of Doom" and the elvish words, variations and place names brings up nothing not already covered. At this point, it's
DIGEST ALL THE INFORMATION and USE YOUR IMAGINATION
What were the eight thrones made of? Who sat where, exactly? What decor did they have? Where did the other Ainu and Eldar sit or stand to witness? What was the floor and ceiling? What marks the edge of the circle?
My imagination supplies these answers:
On grassy, green hill, under the starry sky, at perfect triangle point to the boles of the Two Trees, an open circle of eight stone thrones and a space for a ninth toward Valmar gates is surrounded by larger circles of stone seating, ringed about with rivlets of light. Each throne is inscribed with motifs of the intended occupant in this order: Melko (the missing throne), Oromë (trees), Yavanna, (animals), Aulë, (mountains), Varda (stars), Manwë (wind and globes), Mandos (lines), Nienna (tears), and Ulmo (water). Other named and unnamed Ainu and Eldar will have seats nearby, not so grand but equally personal.
When and if it gets built, I'll share an image or two.