With a history as rich and convoluted as any place in the surface world, the Underdark is especially strange because of the many different races that live there and the natural magic that seeps out of the cavern walls. Words and names created by drow, duergar, svirfneblin, and mind flayers can stick on the tongue and confuse even an experienced reader or traveler. Here's a summary of some of the more important -- and more dangerous -- parts of the Underdark beneath the surface lands of the North. Be wary.

Acid Aerie: Acid Aerie is a gorge several hundred feet across carved by a lake of green, glowing, foul-smelling acid. It is the legacy of some past wizard's experiment. Dozens of interconnected narrow stone walkways ranging from 1- to 10-feet-wide crisscross the chamber. Many lead into side corridors and the tunnels of the Wormwrithings. Zaknafein, father of Drizzt Do'Urden, was killed in his vengeful undead form here.

Ammarindar: The dwarven realm of Ammarindar existed when Netheril did, but its inhabitants abandoned it nearly 500 years ago. Its extensive tunnels reach from the surface to the upper levels of the Underdark, and many creatures now use it as a lair, including orcs and demons. The realm was known for its adamantine armor, and caches of riches too heavy to be taken away in the hasty retreat of the dwarves remain buried in secret places here.

Araumycos: Araumycos, a great fungus, fills the Underdark beneath the High Forest between one and three miles from the surface. Possibly the oldest living organism in the Faerûn, the fungus predates the empires of the elves. It cannot reach beyond the borders of the forest above it and pieces of it taken away quickly die, so it may be magically or symbiotically tied to the forest. While susceptible to fire, acid, and similar attacks, it is immune to magic and no endeavor has eradicated much of it for long. In fact, it sometimes unleashes mental attacks upon its aggressors. Occasionally entire portions die, revealing ruined cities or colonies of fungus-folk, but the cause and origin of the growth remains unknown.

Blingdenstone: Founded over two thousand years ago by svirfneblin (deep gnomes) fleeing the phaerimms, Blingdenstone formed the seat of a self-sufficient city-state that only rarely made contact with other nearby civilizations. Jolted out of their isolation by Menzoberranzan's attack on Mithral Hall, the deep gnomes chose to ally with the dwarves. The defeated drow later had their revenge after spending several years gathering power and finally summoning two dozen bebiliths (spider demons) into Blingdenstone, which slaughtered most of the svirfneblin. The five hundred or so survivors fled with their belongings to Silverymoon, where their small community was welcomed into the Alliance of Silverymoon. The people of the Silver Marches hope to resettle and fortify the city, using it to draw attacks by Menzoberranzan away from Silverymoon.

Buiyrandyn: Buiyrandyn, a tiny drow settlement, was famous for its rejection of Lolth and the other evil drow deities. Mind flayers destroyed it centuries ago, and it has since been inhabited by other monsters. Few know it, but Buiyrandyn was the birthplace of Qilue Veladorn, one of the Seven Sisters.

Cavern of Cloven Heads: The site of a long-ago battle between drow that would eventually found Menzoberranzan and a rear guard of dwarves from the Black Axe Clan, the Cavern of Cloven Heads was abandoned with Ammarindar. Since then, tribes of Uthgardt barbarians have claimed the cave, and over generations they have degenerated and mutated into blind, cannibalistic grimlocks.

Chaulssin: The strange ruin of Chaulssin was once a drow city. Long ago conquered by shadow dragons, the drow inhabitants overthrew their draconic masters. These drow later mastered shapechanging magic and transformed themselves into dragon form. They eventually pooled their magic to shift their entire city to the Plane of Shadow, leaving only flickering shadows of the creatures that used to live here.

Ched Nasad: The City of Shimmering Webs is in a great V-shaped cavern under the northern Graypeak Mountains. The city is Menzoberranzan's closest significant rival, and a council, composed of the matron mothers of the twelve highest-ranking noble houses, rules it. Upwards of two thousand visitors reside in Ched Nasad at any given time, including powerful creatures such as aboleths, mind flayers, and fiends. The drow have warred with nearby beholders for centuries and do not tolerate their presence in the city. Their main trade goods are body dyes and other augmentations, casks and pottery, everdark ink (made from deep dragon scales dissolved in acid and prized by wizards), finely made armor and weapons, Netherese artifacts, molds, poisons, potions, riding and subterranean lizards, rothé wool, meat, cheese, spells, textiles, and water. The city was founded by exiles from Menzoberranzan after a furious battle between rival noble houses.

Darklake: South and east of Mantol-Derith, Darklake is a series of connected bodies of water that were formerly linked by waterfalls but are now governed by locks created by dwarven engineers. The caverns are used as a relatively safe passage by duergar (deep dwarves), although the place has its share of monsters (mainly freshwater trolls and a type of evil intelligent freshwater manta ray). There may be a portal that connects the Darklake to one of the underground rivers servicing Skullport, and if the portal and its activation key can be discovered, it would greatly facilitate trade between the Underdark and the surface.

Entemoch's Boon: The cavern called Entemoch's Boon is a holy place to the deep gnomes of Blingdenstone. Three stone pillars stand in the center of the cavern floor, and each bears runes of powerful Conjuration magic. Spells tied to earth and the Elemental Plane of Earth are enhanced here, and summoned earth elementals brought forth in this place are always exceptionally powerful. The magic also aids in the creation of magic items related to earth magic. Unknown to the gnomes, a hidden gate to the Elemental Plane of Earth exists that opens only after an earthquake or similar disturbance.

Fardrimm: Fardrimm was used to describe the area once held by the dwarven kingdom of Delzoun at its height. The region's mineral wealth has been depleted over many centuries, and the dwarves have lost much of their original territory to orcs, phaerimms, and other creatures. However, they are still the most populous race in the area. They maintain many links to the surface, including the lower levels of Citadel Adbar and Citadel Felbarr.

Gargoyle Tube: Gargoyle Tube gets its name from the gargoylelike monsters that hunt near here. The bottom of a great lava bubble, it is rich in gem ore, and as such it is frequented by kobold and deep gnome miners. Tunnels from here reach to the Dungeon of Death near the surface, and one demonic resident of that place hunts here, making the place far more dangerous with its presence.

Gauntlgrym: Little is known about this place other than it is a city of mind flayers.

Gracklstugh: Also known as the City of Blades, the duergar nation of Gracklstugh is just south of the Trollmoors. The nation consists of a large grotto of hollowed-out stalagmites that borders the Darklake, and the gray dwarves use the stone pillars as smelting centers and also build their homes and workshops around them. The duergar control territory for several miles around their home city, allowing in only visitors intent on trade, and they have a large standing army to enforce their claim. The city holds many duergar, derro, slaves of various races, and a clan of stone giants. The city exports fish, mining equipment, and quality steel arms and armor. The derro are the true rulers, controlling the duergar king and the clan leaders with bribes, magic, and threats. Gracklstugh has a large standing army and patrols its borders often.

Mantol-Derith: Located more than three miles underground, Mantol-Derith is a set of caverns that serves as a crossroads of commerce, news, and migration among the civilized races of the Underdark. Equidistant from Menzoberranzan and Blingdenstone, it is uncomfortably close to the Darklake and so it remains neutral ground. It is one of the few places where the drow of Menzoberranzan, the duergar of Gracklstugh, the svirfneblin of Blingdenstone, and a handful of surface dwellers meet in uneasy truce and trade for otherwise unobtainable goods. The cave of Mantol-Derith is a large natural grotto, with an excavated cavern nestled in each of its four corners. The ceiling of the central chamber is a grand dome that stands nearly 100 feet high in the center.

Menzoberranzan: North of the Trollmoors and under the river Surbrin, Menzoberranzan is a matriarchal drow city most famous for being the birthplace of the Drizzt Do'Urden and the launch point for the attack on Mithral Hall. The city's population is only one-third drow citizens, with the rest being humanoid slaves. The city trades poisons, tasty mushrooms, riding lizards, spell scrolls, wine, and water. The city is defended by drow troops (both full-time soldiers and armed members of the noble houses) and slave forces, with many spellcasters aiding defensive efforts. Although ruled by a council of matrons from the eight greatest houses, others in the city hold much political power such as the mercenary leader Jarlaxle and the Archmage of Menzoberranzan Gromph Baenre. Although the drow are generally cool toward visitors, a few small businesses cater to adventurers and traders. Over a hundred tunnels link the outskirts of Menzoberranzan's territory to other parts of the Underdark, with the most notable being near Mithral Hall, in the heart of the Moonwood, and on the western edge of the High Forest. The city has recovered from its losses during the Time of Troubles and the attack on Mithral Hall, and it is again planning expansion and conquest of its neighbors and the surface realm. One of the primary targets is the city's Vhaeraunian drow that have migrated to the forest of Cormanthor via a gate once used to raid the rival drow city of Nar'Vheen.

Sschindylryn's Gate: Sschindylryn's Gate is a portal to an unknown plane that was discovered by scouts from the city of Sschindylryn. Sschindylryn is a drow city under Cormyr known for its use of portals to explore and conquer other parts of the Underdark. During a battle with Menzoberranzan, the portal was damaged, and none from the western city know how to operate it or to where it leads.

Stoneshaft Clanhold: The small and almost-forgotten clan of dwarves called Stoneshaft Clanhold has suffered setbacks in recent years, including a large slaving raid by the Zhentarim. They have escaped to their old tunnels and are hard at work reclaiming and securing their old territory. They prefer to be left alone and maintain only a few contacts with the surface for trade purposes.

The Wormwrithings: The Wormwrithings are twisting tunnels -- possibly carved by purple worms -- that cover a large area to the north and west of Blingdenstone. Many small tribes of kobolds dwell here, and they constantly battle larger predators such as umber hulks, basilisks, and deep bats. The Blingdenstone gnomes follow recently-made purple worms tunnels in this area, hoping to find new veins of precious metals and gems.

Yathchol: The cavern called Yathchol holds a cluster of villages populated by chitines (drow-spider crossbreeds created by the drow of Ched Nasad as an attempt to create an ideal slave race). Cast out by their creators, the chitines thrive here and guard their homes with carrion crawlers.