Montor
Montor is a ruined city in the Ilshenar facet.
It is near the Shrine to Chaos.
Various demonic creatures (see Abyss Slayer) creatures spawn here, and a lava pit in the norhteast section was labeled on UO Automap as a gate to the Abyss. Certain fire-based creatures, such as Dragons, also spawn here.
While there is not much official fiction on Montor, that it was destroyed by demons, in Magincia-like fashion, is not a hard guess.