I'd have to check nearby FATE text to be sure, but as far as I can tell there's no info about the place beyond Conrad mentioning it was an abandoned ruin (frustratingly leaving it at that). But I'm in 100% agreement with V'aleera that its name suggests a connection to Nael van Darnus (aka the "White Raven") and the doomed VIIth Legion who later all perished on Carteneau. Towards the end of 1572 Nael was transferred from the eastern theatre to assist Baelsar take Eorzea. This resulted in a massive uptick in labor and military fortifications across Gyr Abania. It's possible, if not likely, that Castellum Corvi was Nael's base of operations during this time and as the VII Legion stole into Eorzea to build Castrum Novum in Mor Dhona to house the second incarnation of Meteor Project.
