Pit Wall
The wall directly on the rim of the Kirinal Pit is garrisoned every day around the clock. Each of the Eight Cantons that are members of the Concordance for Survival built the section of the Wall assigned to them.
The Wall is roughly 94.25 miles in circumference with battlements along the entire length. A signal tower stands at every mile marker of the Wall and one of the Eight Great Fortresses stands at the cardinal (N, S, E, W) and ordinal (NE, SE, SW, NW) points of the Pit. The Concordance specified that the Wall should be built of stone or metal and be at least 30 feet tall and 20 feet wide.
Conventional Defenses
On Days of the Week which could possibly become "Days of War", the Pit Wall is fully manned with a full garrison of Kirinal Pit Defenders and an archer or rifleman at every crenellation in the Wall. The great skyship dreadnaughts of each Canton floats above their respective fortress ready to repel extraplanar invaders.
Arcane Defenses
The Wall's entire length is warded with defensive magic to repel undead, fiends, aswang, and evil spirits. These low level abjurations keep out most minor invaders. When a greater spirit or power breaches the Wall, an alarm sounds that draws the closes Defenders to investigate it.
Additionally the walls are hardened against transformation. The entire Zone is warded by Teleport Sinks that re-direct teleporters into dimensional jails in the main Embassy City for that slice.
In times of greatest peril, when a Great Old One or a horde of xenomorphs manifests in the Pit, the Great Wall of Force can be deployed until the next dawn. The Great Wall burns through magical energy and takes months or years to replenish, so it is used as sparingly as possible.
You have to love an impenetrable wall. It always makes it more interesting to tear down. :) Yours is one of those worlds I really need to take a deep dive into...
Thanks for the like and the comment! I'd say it's less "impenetrable" and more "well-defended". Stuff definitely gets through and the people of the Zone know it does! See my "Celebration of Children" article for some of how they deal with it.
Learn about the World of Wizard's Peak and check out my award winning article about the Ghost Boy of Kirinal!