Beneath the tall peaks and twisting caves of the Everfall Mountains lies a vast network of tunnels that spans continents. This is the second sublevel of the Underdark, and the home of the drow after their corruption during the War of Magic. Whilst the drow have thousands of cities, towns and villages across Istralar, each area's drow civilisation tend to build their own capitals. Vaermyrhel is the 'capital' of the drow across the Aletheian Empire, having intentionally declared their independence from other drow societies even before the Empire had begun its expansion. A number of the noble Houses have built their castles and mansions to the northern side of its cavernous reach, though the recent civil war has left many of these empty or in significant disrepair. Lesser Houses have begun to move into the formerly-great homes as a result. The largest of these is the castle belonging to House Umbra, which seems to draw in the light around it - a result of significant amounts of umbrite and shadow magic being woven into its construction. House V'drath's former home, the Castle of Monsters, was completely destroyed after the conclusion of the war - it previously dwarfed Castle Umbra. In darker circles, the Vaermyrhel slave market is famous for its well-trained slaves of a myriad of races. Slavery may be illegal in most parts of the Aletheian Empire, but the Underdark has always functioned around a slave-based society and Vaermyrhel is no exception. Whilst some of the Houses run breeding programs to ensure they maintain good slave stock, fresh victims who wander in from the surface (or are captured in raiding missions) are also welcomed into the markets - though these tend to require far more intense training. Certain noble Houses have also mastered the art of fleshwarping, and create fleshwarped beasts for their own entertainment and for use in battle. Towards the south of the city lies the Arisen Laboratory, a multi-story facility for mass-producing fleshwarped abominations, owned by House Noqu'rae, the faithful of the Demon Lord Haagenti. The green glow of the fleshwarping vats can be seen from quite far away, and the exposed glass allows any to watch the spectacles happen. This usually draws massive crowds when the victims involved are formerly high-ranking drow or their natural enemies, the elves. At the heart of the city is a large, pulsating pillar that contains an enormous purple crystal. According to the city's historians, it's a shard of their former magical conduit from Terra Arcana, discovered after the Worldrend and rescued. It provides a soft purple light across the entire city, enough to illuminate where darkvision fails to reach. The city is fairly easy to navigate when one has a sense of what they're looking for. The northern reaches are the residential districts, the west holds slave markets, training arenas, mines and breeding pits, the south holds a mixture of alchemical, arcane and divine shops, specialists and items, and the eastern area is purely industrial: great factories to churn out weapons, armour and vehicles for the city's multitude of armies to use. The centre is generally reserved for rare inter-House meetings, public executions/torture, and the use of magical rituals (using the crystal as a conduit). The dregs of society (freed slaves, weaker outsiders, drug-abusing lowborns and other homeless or extremely poor citizens) are consigned to life outside the city's walls, in a violent slum that extends through many tunnels to the city's south.
If slaves and fleshwarped monstrosities aren't included, the city is 90% drow. Stronger descendants of outsiders often choose to live in Vaermyrhel, either as part of the noble Houses or as independent mages (if they're female).
As all drow societies are, Vaermyrhel is a strict matriarchy - men are considered second-class citizens. The most powerful House rules the Underdark - and right now, this is House Umbra. Usually, power transfers by assassinations and subtle political manoeuvres (the events in Yuethin'tar, for instance, reduced the standing of House Arkenviir significantly). There are very few laws, and even fewer actively enforced. Drow are expected to swear fealty to a specific Demon Lord (and thus, noble House) for protection whilst young. Rare occasions see trades between Houses (such as beautiful women and handsome men between House Umbra and House Lastheria), but most drow remain loyal to the same matron and Lord throughout their lives.
The main city is circled by a tall wall reinforced by steel made from the weapons and jewellery of former victims. The outside is layered with enchantments, traps and alarms. Regular patrols of guard squadrons along the wall and inside the city prevent any unwanted trouble from invading forces, and a series of scrying crystals placed throughout the cavern's ceiling watch for strange actions or magics.