A number of the Planes of
boxed sets mention what the portal to the Outlands looks like on the various planes. While it's possible that these are one-way portals, I assume they're two-way and that the "other side" of the portals are the portals in the Outlands gate-towns.
Ecstasy - You emerge from a dark cavern (according to the 1e Manual of the Planes
) on the shore of the River Oceanus, a day's travel from the guardinal city Release From Care.
Sylvania - I'm pretty sure you end up in Thrassos (there's a portal to the Outlands in Thrassos's square, and also a mention of vineyards near Sylvania sliding to Thrassos)
Glorium - This one's tricky. The main portal to Ysgard is a maelstrom in the middle of Glorium's fjord and you end up in the sea in Ysgard, off the coast of Asgard (Bast's realm is on the other side of the sea). The closest thing to a "gate-town" in Asgard is the city of Himinborg, though the "gate" there is Bifrost, not the sea-gate. You can also travel between Glorium and Ysgard via Yggdrasil.
Plague-Mort - The portal to the Outlands is beneath Broken Reach, so I assume that's where you emerge if you cross through Plague-Mort's gate.
Torch - Void's Edge
(I made this one up). In canon (based on A Player's Primer
and the 1st edition MotP), it would simply be a subterranean cave within Gehenna's first furnace, above a black chasm in the cavern floor that leads to the scarlet orb in Torch's sky (which is why it's best to be able to fly if you want to use Torch's gate).
Ribcage - Darkspine, a former gate-town to Baator now in ruins in Avernus.
Excelsior - Heart's Faith (on the shore)
Rigus - The Battle Cube. There's no town nearby, though there are orc and goblin cities on the other faces. See Lord of the Iron Fortress.
Automata - The 1st edition Manual of the Planes
says the Outlands gate to Mechanus leads to Regulus, on the smooth underside of Primus's gear. The Player's Primer to the Outlands
says where they come out depends on the time of day, the position of the gears, and many other arcane factors, so the portal shifts to many other parts of Mechanus as well. Haven is another confirmed possible destination (Planes of Law
Fortitude - The woods between the Citadel of the Lightning and Wind Kings, according to Planes of Law
. Note that after the events of Fires of Dis
, the former town of Fortitude should be here.
Faunel - Signpost? Wrath can send you pretty much anywhere in the plane, but Signpost would be a good first stop.
Tradegate - Yeoman is the most likely place, though the Master Trader can send you anywhere in Bytopia if the price is right.
Bedlam - There are actually a half-dozen gates to Pandemonium in Bedlam, and it's likely they lead to at least that many different places. The Madhouse, built at a crossroads, is probably the first town you'll encounter there.
Xaos - According to The Great Modron March
, the portal on the other side of Xaos is in a region even more
chaotic than the rest of the plane. It's detailed in that book.
Curst - I assume you end up near the Bastion of Last Hope. Not canon, but this is the most neutral of Othrys's cities, and therefore the closest to the Outlands.
Hopeless - Morglon-Daar
from 4th edition's Demonomicon
works really well here.
Here are the descriptions of what the portals of the Great Road look like on the various Outer Planes, as recounted in the 1st edition Manual of the Planes.
Acheron: Portals take the form of spheres that hum when they're activated; Acheron's cubes slowly orbit around them. Discordant spheres lead to Baator, harmonious ones lead to Mechanus, and silent spheres lead to the Outlands. Planes of Law says there are also portals on the surface of the cubes, so you don't always have to get there by flying or falling; the portal from Rigus is one of those, on the surface of the Battle Cube, looking very much like the Lion's Eye gate does in Rigus itself.
Mechanus: Light-green circles lead to Arcadia, deep-red circles lead to Acheron. The portal to Automata is on the featureless underside of Primus's gear.
Arcadia: Portals are arched trellises of white ivory or black steel, with a color pool open within them 10% of the time. If the portal within is black it leads to the Outlands, if it's white it leads to Mount Celestia, and silvery pools lead to Mechanus.
Mount Celestia: Portals resemble large blocks of finished stones. Black granite shot with gold leads to Arcadia, white granite shot with silver leads to Bytopia, and red blocks spattered with blue flecks lead to the Outlands. The portal to Excelsior looks like a bobbing light hovering over the ocean, according to Planes of Law
; you have to chase it down.
Bytopia: Portals appear as caverns with patterns shining within. Concentric circle patterns lead to Mount Celestia, radiating lines lead to Elysium, and spiderweb patterns lead to the Outlands.
Elysium: Portals are dark caverns with no clues to which plane they lead. Those that swallow the River Oceanus always lead to the Beastlands, however.
Beastlands: Portals are large openings in hollow trees. These can be any kind of tree, but the same tree always leads to the same plane.
Arborea: Portals are crimson disks, usually surrounded by stone walls or iron gates.
Ysgard: Portals are wells. They are often marked, but tend to be unreliable.
Limbo: Portals may be wells, doors, pools, bottomless openings in chaos, archways, etc - they are usually more stable than the surrounding plane.
Pandemonium: Portals are flat squares on the sides of caverns. Yellow ones usually lead to Limbo, red to the Abyss, and black to the Outlands, with a 1 in 5 chance of error.
Abyss: Portals look like huge holes in the ground, just like the portals to lower layers.
Carceri: Portals are obelisks. Those taller than they are wide lead to the Gray Waste. Those wider than they are tall lead to the Abyss. Those with equal heights and widths lead to the Outlands.
Gray Waste: Portals to Gehenna are great spinning coins of copper, silver to the Outlands, or gold to Carceri. They're visible for miles, and often have iron fortresses built around them.
Gehenna: Portals are deep beneath the surface of the plane, appearing as black chasms in the floor.
Baator: Portals are huge hoops of reddish light, guarded by abishai and amnizu.
Some of the portals on the Great Road are known, by the way. Besides the Outlandish gate-towns, the following are canonical:
Nemmiron (gate-town to Arcadia from Mount Celestia)
Heart's Faith (gate-town to the Outlands from Mount Celestia)
Soul's Desire (gate-town to Bytopia from Mount Celestia)
Pashrita (gate-town in Mercuria, the second layer of Celestia, which leads to the realm of Savitri in Bytopia)
Portal a day's journey from Release-From-Care (Elysium to the Outlands)
River Oceanus (leads from Elysium to the Beastlands)
The Roaring Gate (portal from the Beastlands to Arborea - TGMM, 51)
River Oceanus (leads from the Beastlands to Arborea)
Thrassos (gate-town from Arborea to the Outlands)
The Ingmar Brook in Arvandor leads to Alfheim in Ysgard, presumedly moving through Syranita's realm of Whistleedge. The Gnarl, in Erevan Ilesere's realm, contains a root of Yggdrasil that can also be used to get to Ysgard (or elsewhere).
The River Oceanus (once a month it touches the Gates of the Moon in Ysgard)
Tower of the War Triumphant (portal to the Abyss, not far from Broken Reach, in Muspelheim - Warriors of Heaven, 10)
Yggdrasil (most often used to travel from Ysgard to Limbo; also connects to the Outlands, Ysgard's other layers, the Material Plane, and the Gray Waste)
The Immeasurable (gate from Limbo to the Outlands - TGMM, 67)
The River Styx (touches the first layers of all the Lower Planes)
The Stones of Draedilus (in Othrys, in Carceri, this is a ring of stones that contain portals to Sigil, Gehenna, and the Material Plane - see Hellbound: The Blood War, The Dark of the War, page 57)
Undermountain (on Toril, has a series of portals leading to the Lower Planes - during the most recent March, the modron's used this dungeon to travel from Carceri to the Gray Waste)
Resounding Thunder (in Acheron, contains Nihao, the gate-town to Mechanus, and Eight-Devils-Laughing, the gate-town to Baator; this realm is also occasionally the end-point of the gate to Rigus)
The Blue Cube and the Battlecube are also occasionally destinations of Rigus' Lion's Gate portal.
Grashmog, in Clangor (the goblin pantheon's realm), includes a portal to Forgegloom in Hammergrim (the duergar pantheon's realm in Thuldanin)
The town of Hopeglimmer in Hammergrim has a portal that leads to the Mines of Marsellin, which also contains a portal to Mechanus.
Regulus (in Mechanus, contains portals to Celestia, Arcadia, Acheron, Automata, Baator, and Sigil)