Walls of Night
In the North and South, Ekkaia was narrower and the Walls were closer to the north and south lands of Arda.
In East and West, Ekkaia was wider and the distance from the land was greater; the Door of Night was an opening in the west. The Gates of Morning are also mentioned, but it is not known if these were an equivalent eastern opening on the same Walls.
Presumably Melkor fled through the Walls after he retreated from the First War. During the Spring of Arda, he came over the Walls of Night into the north of Middle-earth, and secretly built Utumno.
Other versions of the legendarium
Originally, they were called the Wall of Things, and conceived as "the walls of terrestrial cities, or gardens - walls with a top: a "ring-fence". In the Ambarkanta they're called Ilurambar, and they're as a shell that fence Vaiya and the world from the Void that are totally impervious and their only opening is the Door of Night.
|Constellations||Anarríma · Durin's Crown · Menelmacar · Remmirath · Soronúmë · Telumendil · Valacirca · Wilwarin|
|Stars||Alcarinquë · Borgil · Carnil · Elemmírë · Helluin · Luinil · Lumbar · Morwinyon · Nénar · Star of Eärendil · Til|
|The Airs||Aiwenórë · Fanyamar · Ilmen · Menel · Vaiya · Veil of Arda · Vista|
|Narsilion||Arien · Moon (Isil, Ithil, Rána) · Sun (Anar, Anor, Vása) · Tilion|
|See also||Abyss · Arda · Circles of the World · Eä · Timeless Halls · Two Lamps · Two Trees · Void|