Barachiel's Horn is an extinct volcano on the Azure Plains, and is best known as the High Gate of Gravitopolis (as opposed to the seven surface-level Low Gates) From the first contact with the city until the Gravitopolis War, the mountain was a major commercial port, with an extensive high dock built around the summit. An ingenious system of lifts allowed dock workers and cargo easy passage from the surface to the city below. There is some evidence that the central chamber of the mountain was sufficiently large to allow sufficiently small craft to pass directly through the gate.

During the war, the Horn took on added strategic significance. Nearly all commerce ceased, and with startling rapidity the commercial port was converted to a military shipyard. Though primarily the Gravitian Fleet acted as a defensive force, forestalling attacks against the Low Gates and their surrounding outposts, there are records of several more daring and aggressive raids.

Controversies

Scattered evidence indicates that there was dispute among contemporary scholars regarding the origin of the Horn. While the volcanic theory best explains the geological structure itself, other theorists would have it that the mountain itself is merely a refuse pile left over from some ancient excavation that created the caverns that house the city. A cryptic passage in the Iron Codex which refers to "the first builders / the first diggers / who breached the sky / and saw the stars" has been construed as evidence for an artificial origin to the Horn, though, as with so many passages in the Codex, such speculation remains quite tentative.

The origin of the name of the mountain is also subject to debate, though evidence is mounting that it is a reference to the semi-mythical founder and engineer of Gravitopolis referred to in other contexts as "The Mole".

—Thaddeus Rhagfarnllyd