Planar Spires

Each major Plane of Existence possesses a Planar Spire, which acts as a sort of anchoring point for the magic of the realm.

Each Spire is a towering shard of pure Mithral that connects to each of the other Planes' spire, though most also have some sort of construct erected around it, like the tower in Eodur or the castle within the City of Brass on the Plane of Fire. Because of their interconnectivity, some even believe that they are all the "same" Spire represented in each Plane.

Regardless of whether or not they are the same structure, it is clear that these Spires act as a sort of "pin" that acts as the fulcrum for each plane of existence and is integral to their interplanar motion and the Convergence of the Planes.