Sulfuron Spire



Sulfuron Spire is the fortress of Ragnaros and the entrance to the Firelands, located in the middle of The Throne of Flame at the southern end of Mount Hyjal.

Speculation
The Inner Spire is presumably inside of it. Unlike other flamegate-entered locations, the Inner Spire appears to be under the spire, and not the flamegate it is entered from.