Pandaemonium's Current Whereabouts (Anabaseious Spoilers)

[Cilia]

Kind of an inverse of the Omphalos. Which makes sense with Pandamonium being the hell to the 12's heaven. Thematically speaking within the patch content, I mean; not that Panda is the actual 7 hells.

... Though apparently Athena does say the term "7 hells" at some point, so maybe there is some kind of connection between the facility and the myth of the 7 hells of the Twelve? I dunno.

She says it as part of her incantation to cast [Theos's] Ultima, which is a callback to Lahabrea's casting of the spell after the first fight against the Ultima Weapon, both using the Heart of Sabik as a catalyst.

From the deepest pit of the seven hells to the very pinnacle of the heavens, the world shall tremble!

Given there's no true divinities in XIV's setting (that we know of, yet) and all souls return to the Underworld / Aetherial Sea / Lifestream, they really should know better, but that line was probably written before this much worldbuilding was done so...

On topic, like all remnants of Amaurotine civilization Pandaemonium was more than likely destroyed either in the Final Days or the Calamities on the Source. It might be possible to find some weathered ruins on some of the reflections, but despite their superior construction quality even Amaurot itself was in extreme disrepair on the First. Granted that was underwater, but even so.