The Scar / Ground Zero

((This is a rough idea that may be dismissed later on))

The Scar is an area in Aevum covered entirely by mutliple powerful barriers, and surrounded by a forcefield erected between tall, obsidian stone pillars. It surrounds what once was Aevum's largest magitek facility, but is now nothing more but distorted rubble, known as Ground Zero. This place is where the First Rupture took place, in which what was supposed to be a controlled hell gate suddenly exploded into a giant, gaping portal into the deep of the abyss. Out from it, waves of demonic essence spilled, melting a good part of the city, and distorting reality around ground zero enough for powerful demons to step out of the portal, and for countless lesser ones to form.

Immediately, the city was on high alert, and everyone that had at least some fight in them did their best to push back the demonic forces. The fight cost millions of lives, and destroyed huge chunks of the city - some permanently. At some point, the sun god Sol ((or possibly a mortal that was either empowered by Sol, or would become him later on)) pushed through the fray enough to reach the heart of the distortion and hold the gate closed enough for his allies to create a more permanent solution. Sacrificing parts of their own bodies, powerful chains and spell circles were forged to close the gate and prevent it from ever opening again.

However, the gate still exists - it is just a dot by now, chained and locked in a tightly interwoven ball of divine and arcane magic, but it is a dot that exists and could destroy everything again in a moment. As such, access is entirely forbidden. And, more interestingly, knowledge about what actually caused The Scar is also being falsified. While in reality, it was humans experimenting with forces beyond their control that caused it, the public is taught that it were the dragons that attacked Aevum, and, in the middle of the city, opened a portal to the homeworld of demonkind for the first time, only to be defeated by the brave and powerful gods on our side.