Faux Gates News:  Once just one, there are now 12 of these false-gate outlines left faintly visible, apparently chiseled into the Perimeter Wall.
Faux Gates
Faux Gates

On the outside faces of the Perimeter Wall, as yet another clever, tactical diversion and deception on the usual Titanic scale of the Inisfreean people, are these features which give the misleading appearance of being the gate outlines leading into this massive wall's airlock and scanning chambers.  Positioned many hundreds of feet off to the side and away from the actual gates, these stadium-sized rectangles of the sheer ice cliff serve to draw potential incoming fire away from the actual gates long enough to allow for surprise and massive troop and other movements both into and out from the actual gates.  They are also positioned such that any extremely large blast and shockwave, such as from a nuclear barrage, would only help further seal and harden the actual gates and passageways; like the internally-hidden, rotating spheres that make up the second and fourth chambers of each gate's passageway sequence, this design, too, becomes stronger and more immovable the more it is attacked.

Seeing Fake Gates Misleads Enemies into Assuming the Real Gates have Weakpoints:
This is just another clever Inisfreean tactic, though, for all things Inisfreean are nearly impossible to destroy.

I​​t is also of note with this feature of the Inisfree city design that it is part of the virtually unchangeable collective construct that is the Inisfreean realm.  That is to say that its 'smart'-structure, sandwiched armor, shielding, and other aspects make it invincible even to thermonuclear, supernova, black-hole, and anti-matter weaponry, as well as, of course, the whole host of magical powers that any outsider may have learned.  These fake gate hatch outlines can draw and hold fire by both appearing as the actual gate hatch outlines and constantly re-building and re-forming themselves, giving the false impression that, perhaps if the enemy concentrates more firepower upon them, they won't be able to re-form as quickly, and will eventually break open to reveal a passage into the city's interior.

​​In the unbelievably unlikely event that a nonstop barrage of such god-like projectiles was both produced and successfully launched at a pinpoint target anywhere along or upon the Inisfreean realm, be it a single spot on this Perimeter Wall or anything else, if the Grid Mind and Inisfreean Master Female Storm Troopers were somehow not able with all their coordinated supercomputer brains and 'smart'-gear to delete, redirect, backfire, send erratic, teleport, deflect, absorb, and/or convert all of such incoming fire with their usual, casual ease, not to mention their abilities to calm any creature down, change their minds, and even make them turn on their comrades or even submit to the Inisfreean will entirely, the fraction of the projectiles miraculously making it through all of these Inisfreean abilities and defenses would then have to make it through the consecutive shield spheres that surround Inisfree city like perfectly spaced bubbles within bubbles, each one drastically changing the density and vibrations those projectiles would have to course-correct and compensate for.

​​Then, said remaining projectiles would have to make it through the literally tens of thousands of 'rainbow canons', each of which is a 'smart'-gun capable of engaging multiple targets simultaneously with projectiles (both bullet-like and plasma-burst) which self-pilot and accept course corrections from their firing platforms.  These 'rainbow canons', named for their ability to adjust their emitted projectiles to nearly anything imaginable (flash-cloning entire belts of ammunition the split-second their target analyses determine what would damage their targets the most), are also constantly re-analyzing their targets to maintain pinpoint-accurate beam-fire on each of their targets' areas which become the most vulnerable and weakened throughout the offensive.  In other words, as different spots on each target become more damaged and likely to result in a catastrophic kill of the target, it is those spots which are instantly detected and exposed to more concentrated fire.  The result is that streams of many kinds of bullets and lasers are emitted as quickly as the rounds from a Gatling gun, and since they often change type mid-stream to continue being as effective as possible against their changing target (how targets change as they take on more damage), these streams of fire may include as many colors as the rainbow.

Lastly, whatever is left of such an impossibly unlikely barrage of incoming fire would impact the Perimeter Wall which is nearly a full mile thick (and much taller if you count its depth below the ice that is ground-level); a wall whose composition is that of 'sandwiched armor', meaning it has many, many layers of different armor types, causing the dispersion of the force of any impacts to be so erratic that within mere inches to feet... nothing is felt at all.  That, and everything built by the Inisfreeans is self-repairing; like carbon-fiber nano-tubes, it grows back to the exact form it is hard-wired to, so whatever damage said unlikely barrage was able to pull off at this point... would start to fade away right before the enemy troops' and commanders' eyes.  It would appear as if the Perimeter Wall (and any damaged 'rainbow canons' or other Inisfreean constructs) were healing as quickly as vampires are said to.​​  Much of the energy from those impacts would also be used to accelerate this biomechanical healing process -as would any shrapnel, even if it was radioactive.

So if any incredibly vast, nearly endless Outlander military force was able to notice the Inisfreean Perimeter Wall many miles within its aetherial, outermost sphere of airspace and territory (a sphere which blurs, masks, and cloaks all of Inisfree city from any form of Outlander detection -even that of satellites), and if, somehow, that force was also able to get past the honeycomb formation of Sentry Towers (Inisfreean Dropships) encircling Inisfree with overlapping fields of 360°​​ fire, and if, after that, this force was able to launch a wall of projectiles so dense and long-lasting that it got past all of those aforementioned Inisfreean abilities, any damage it caused would be upon a fake gate hatch outline, doing the enemy force absolutely no good, while further energizing and recharging Inisfree as a whole, and whatever was left of that enemy would still have multiple, successive, concentric rings of hidden trenches, moats, tank-traps, 'dragons-teeth' barriers, traction-less ice terrain, proximity-activated electromagnetic tractor-beam pits designed to suck in body-armored infantry and vehicles, an un-climbable ice cliff Perimeter Wall so tall it would take an expert climber with no distractions or setbacks what-so-ever more than a week to scale, and an actual gate hatch still so well-hidden it is literally imperceptible, not to mention hundreds and hundreds of feet up above their ground level at the base of this sky-high wall.  That, and nothing they have in their arsenal could be powerful enough to burrow through a nearly mile-thick wall that constantly heals and reseals itself.  Plus, the entire city can always just teleport away, leaving them with nothing left to attack but a five-mile-deep crater where Inisfree used to sit.

Distinguishing the Undistinguishable:
The actual rectangular hatches that open to allow traffic into and out from the first chambers of the Pearly Gates are so well crafted that they are imperceptible to the naked eye.  The only semblance of a gate hatch outline are the Faux Gates, as they are called, but even they seem far too large to function as hatches of any kind.  It is entirely probable that all of those rare and lucky enough to inadvertently enter this outermost sphere of the Inisfreean realm wouldn't even notice them, not knowing what they are looking at, let alone that Inisfreean architecture is typically on this incredibly large scale.