Leyawiin was developed for Cyrodiil: Dawn of Oblivion, a mod by Shenna & Vality. Leyawiin - a self-contained, all-interior city for Morrowind, was eventually released as a self-contained mod. It is a recreation of Oblivion's southerly city, based on the concept art, set 18 months before the start of Oblivion.
True to pre-Oblivion descriptions, Leyawiin
is tropical rainforest