Portal Monoliths

Portal Monoliths, or just portals, are mechana in the shape of a rectangular slab made of granite. Each such monolith is inscribed with a series of symbols--called a Sigil Sequence--that is unique to each portal.
Portal Monoliths are enchanted to function just like the Permanent Teleportation Circles found in other D&D worlds. Unlike such circles, which are permanently tied to their respective locations, the monoliths can be moved (though this is by no means a simple task).
Generally speaking, the people of Erdos do not use teleportation circles, they use portals.
The spells teleportation circle, teleport, plane shift, as well as any other similar spell, interact with portal monoliths the same way they'd do with permanent teleportation circles.
Erdosian magicians have also developed another spell, called Linked Portal, which is very prominently used for teleportation on the world.
Portal Monoliths are found in many cities. They are usually well-guarded, and tolled for being used. Magicians that can cast the linked portal spell as a ritual, can open portals for travelers.
Portaling, as this method of travel is called, is expensive, and is thus mostly used by wealthy individuals who travel is small groups (as a portal can only remain open for about 6 seconds for each casting of the spell). Most people still rely on caravans, horses, and skyships for long distances.
There are also many forgotten monoliths in remote regions of the world, some dating back to the Age of the Varn.

Discovery

Port