A teleportation chamber is an area within a rune-carved geodesic dome. They are built to magically transport things between two fixed places on the same world. Owners of these devices, large empires or those ridiculously wealthy, create fortresses around them.
To contain the arcane energy inside them, with tendrils ever so lightly touching the Weave, the minimum size of a teleportation chamber is 40' across. As a result, they are often constructed underground or with an entire fortress built around them. A possible invasion point, owning a teleportation chamber comes at great risk.
- Zarrek, before the Malacost Sentinels - "Project Angel"