These "Elf gates" can occasionally be seen over the Qabarat skyline. They appear as little more than a huge undecorated arch (like the St. Louis Arch). Unlike a mundane arch, when a person or object breaks the plane of the arch, they start to disappear and reappear at a paired arch.
The direction of approach matters and is strictly controlled with one side being an entrance and the other the exit. After all, one wouldn't want to start materializing in the same space where someone is already standing.
There are 11 that link to other locations on Castrovel and 6 that are one way trip to unknown locations. Hopefully safe trips but highly unlikely.