KEY:

PLANE
(number of layers)
Special feature
Layer (layer number and name)
   + Realm (key power, powers, or inhabitants)
       * Realm town (influenced by local powers)
       - Site
   # Independent town or independent site

THE ABYSS
(infinite, interchangeable layers&realms -
numbers only refer to the order in which they were catalogued by the Guvners)
River Styx
Layer/Realm 1: Plain of Infinite Portals
       * Gallowsgate
       * Sryros
       * Broken Reach
       - Lakes of Molten Iron
       - Tower of Chiryn (a succubus)
Layer/Realm 6: Realm of a Million Eyes (beholder realm)
Layer/Realm 7: Phantom Plane (Sess'inik's realm)
Layer/Realm 12: Twelvetrees
       - Ship of Chaos
Layer/Realm 13: Blood Tor (Beshaba's realm; Umberlee's realm)
Layer/Realm 23: Iron Wastes (Kostchtchie's realm)
Layers/Realms 45, 46, 47: Azzagrat (Graz'zt's realm)
       * Zelatar
       * Argent Palace
       - Zrintor, the Viper Forest
Layer/Realm 66: Demonweb Pits (Lolth's realm)
Layer/Realm 74: Smaragd (Merrshaulk's realm; Ramenos's realm)
Layer/Realm 88: The Gaping Maw (Demogorgon's realm)
Layer/Realm 113: Thatanos (Kianansalee's realm)
       * Naratyr
       * Forbidden Citadel
Layer/Realm 181: Rotting Plain (Laogzed's realm)
Layer/Realm 222: Shedaklah (Juiblex's realm; Zuggtmoy's realm)
Layer/Realm 274: Durao (gateway layer)
Layer/Realm 303: Sulfanorum (smoking realm)
Layer/Realm 339: Worm Realm (Urdlen's realm)
Layer/Realm 377: Plains of Gallenshu (Armanites' realm)
Layer/Realm 400: Woeful Escarand (Nalfeshee's realm)
Layer/Realm 422: Yeenoghu's Realm
Layer/Realm 503: Torremor (Pazrael's realm)
       - Onstrakker's Nest
Layer/Realm 586: Prison of the Mad God (Diinkarazan's realm)
Layer/Realm 643: Caverns of the Skull Goddess (Kali's realm)

ACHERON
(four layers)
River Styx
Layer 1: Avalas
   + Lei Kung's Realm
Layer 2: Thuldanin
Layer 3: Tintibulus
Layer 4: Ocanthus

ARBOREA
(three layers)
River Oceanus
Mount Olympus
   + Seelie Court (wandering realm)
Layer 1: Olympus
   # Thrassos
       - Gilded Hall (Sensate post)
   + Arvandor (elf realm)
       * Grandfather Oak (treant independent town)
       - Pale Tree (Solonor)
       - Gnarl (Erevan)
       - Lolth's Grove (abandoned)
       - Roaring Gate (gate to the Beastlands)
       - Sparkling Sea (Deep Sashelas)
       - Ingmar Brook (gate to Alfheim in Ysgard)
       - Evergold/Canathas (Hanali/Aphrodite)
   + Olympus (Greek Realm)
       * Arkenos
       * Thalassa
       * Polykeptolon
       - Mount Olympus
       - Each Greek god's temple or hall
   + Brightwater (Llira's, Sune's, and Tymora's realm)
Layer 2: Ossa (Aquallor)
   # Elshava
   + Caletto (Poseidon's realm)
       * Corilla
       * Pearldrop
       * Coldcurrent
Layer 3: Pelion (Mithardir)
   + Amun-thys (Nephythys's realm)
       * Bal-tiref

ARCADIA
(three layers; two are unexplored)
Layer 1: Marduk
   + Marduk
   + Mt. Clanggedin

BAATOR
(nine layers)
River Styx
Layer 1: Avernus
   # Bel's Fortress
       - Pillar of Skulls
Layer 2: Dis
   # Dis (The Iron City)
Layer 3: Minauros
   # Minauros the Sinking
Layer 4: Phlegethos
   # Abriymoch
Layer 5: Stygia
   # Tantiln
Layer 6: Malabolge
Layer 7: Maladomni
   # Malagard
Layer 8: Cania
   # Mephistar
Layer 9: Nessus

BEASTLANDS
(three layers)
River Oceanus
Yggdrasil
   + Seelie Court (wandering realm)
Layer 1: Krigala
Layer 2: Brux
Layer 3: Karasuthra

BYTOPIA
(two layers)
Layer 1: Dothion
   # Yeoman
   + Dothion (gnome realm)
Layer 2: Shurrock

CARCERI
(six layers)
River Stvx
Mount Olympus
Layer l: Othrys
   + Titans' Realm
Layer 2: Cathrys
Layer 3: Minethys
       - Coeus's Temple
Layer 4: Colothys
   # Gaola
   # Straifling
       - Crius's Temple
   + Grolantor's Realm
Layer 5: Porphatys
       - Oceanus's Temple
Layer 6: Agathys

ELYSIUM
(four layers)
River Oceanus
Yggdrasil
Layer l: Amoria
   # Release From Care
   + Isis's Realm
   + City of the Star (Ishtar)
Layer 2: Eronia
   + Enlil's Realm
Layer 3: Belierin
Layer 4: Thalasia

GEHENNA
(four layers)
River Styx
Mount Olympus
Layer l: Khalas
   + Teardrop Palace (Sung Chiang's Realm)
Layer 2: Chamada
Layer 3: Mungoth
Layer 4: Krangath
   + Shargaas's Realm

THE GRAY WASTE
(three layers)
River Styx
Mount Olympus
Yggdrasil
Layer 1: Oinos
   + Khin-Oin (yugoloth realm)
Layer 2: Niflheim
   + Hel's Realm
Layer 3: Pluton
   + Hades' Realm

LIMBO
(layers undefined)
Yggdrasil
   # Barnstable (independent halfling town)
   # Floating City (independent githzerai town)
   # Shra'kt'lor (independent githzerai town)
       - Pinwheel
       - Spawning Stone (slaadi)
   + Fennimar (Fenmarel's realm)

MECHANUS
(each realm is an individual cog; actual number unknown)
   + Regulus (modron realm)
   + Anu
   + Jade Palace (Shang-ti's realm)
   + Varuna's Realm
   + Rudra's Realm
   + Yama's Realm

MOUNT CELESTIA
(seven layers)
Layer 1: Lunia
   # Heart's Faith
Layer 2: Mercuria
   + Bahamut's Realm
   + Vishnu's Realm
   + Surya's Realm
Layer 3: Venya
   + Yondalla's Realm
Layer 4: Solania
   + Kuan Yin's Realm
   + Moradin's Realm
Layer 5: Mertion
Layer 6: Jovar
Layer 7: Chronias

THE OUTLANDS
(nine layers)
   # Sigil (independent town)
   # Excelsior (independent gate town to Mount Celestia)
   # Tradegate (independent gate town to Bytopia)
   # Fortitude (independent gate town to Arcadia)
   # Ecstasy (independent gate town to Elysium)
   # Faunel (independent gate town to the Beastlands)
   # Sylvania (independent gate town to Arborea)
   # Glorium (independent gate town to Ysgard)
   # Automata (independent gate town to Mechanus)
   # Rigus (independent gate town to Acheron)
   # Xaos (independent gate town to Limbo)
   # Bedlam (independent gate town to Pandemonium)
   # Ribcage (independent gate town to Baator)
   # Torch (independent gate town to Gehenna)
   # Hopeless (independent gate town to the Gray Waste)
   # Curst (independent gate town to Carceri)
   # Plague-Mort (independent gate town to the Abyss)
   + Tir na Og and Tir fo Thiunn (Celtic gods' realms)
   + Sheela Peryroyl's Realm
   + The Dwarven Mountain
       * Ironridge
   + Semuanya's Bog
   + Gzemnid's Realm (beholders)
   + Caverns of Thought (Ilsensine's realm)
   + The Palace of Judgment (Yen-Wang-Yeh's realm)
   + Tvashtri's Lab
   + Thoth's Estate
       * Thebestys
   + Hidden Realm (Annam's realm)
   + Mausoleum of Chronepsis
   + The Court of Light (Shekinester's realm)

PANDEMONIUM
(four layers)
River Styx
Yggdrasil
   + Gorellik (wandering realm)
Layer 1: Pandesmos
   # The Madhouse
   + Winter's Hall (Loki's realm)
Layer 2: Cocytys
   + Hruggekolohk (bugbear realm)
       - Howler's Crag
       - The Harmonica
Layer 3: Phlegethon
   # Windglum
   + Unseelie Court
Layer 4: Agathion

YSGARD
(three layers)
Yggdrasil
   + Seelie Court (wandering realm)
Layer 1: Ysgard
   # Steadfast (independent bariaur town)
   # Skeinheim (independent town of the Ring-givers)
   # Alfheim
       * Frey's Hall
       - Xeno's Tower
       - High Grove
   + Asgard
       * Himinborg
       - Norse gods' halls, including Valhalla and Gladsheim
       - Bifrost
   + Jotunheim
       * Utgard
       * Meerrauk
       * Okalnir
   + Gates of the Moon (Selune's realm)
       * Mahogany
       - Infinite Staircase
   + Merratet
       * Rumm
       * Eowr
       * Bremsiris
   + Vanaheim
       * Noatun
       - Sussrumnir (Freya's hall)
Layer 2: Muspelheim
   + Muspelheim
       * Njarlok
       - Spire of Surtr
Layer 3: Nidavellir
   + Nidavellir (dwarf realm; gnome realm)
       * Ashbringer
   + Svartalfheim (dark elf realm)
       * Dokkar
       * Yggwyrd