Citadel of Dusk

Built on the southern tip of Lustria, the Citadel of Dusk is one of the oldest settlements in Lustria not built by the First Children of the Old Ones. The Citadel is a naval base for High Elf sea patrols. It's their main gateway. The site is saturated with passive magical concealment.
Most seafaring Warhammer factions have to sail around the continent to move between the western and eastern oceans so few ships and fewer fleets make this journey without the High Elves knowing about it. It's also a handy navigation point and potential resupply base for any High Elf fleet on a long range patrol or voyage.
The Citadel detailed on the main Warhammer wiki, but there wider implications for the Scaleverse of Warhammer.
As far as I know, there has never been a major threat to the Citadel of Dusk in official published works by GW. An isolated High Elf base would be vulnerable to an attack by the Dark Elves of course, but it's unclear whether they would have much incentive to do so. The Dark Elves already have a far superior means of traversing the two oceans via an underground sea that acts as a proverbial Panama canal.
It's unclear whether the Slann of Lustria are even aware of the existance of the Citadel of Dusk. While the elf wizards who put a magical concealment spell over the Citadel from casual onlookers were powerful, they are no match for the Slann, but is easily possible that the Slann aren't aware of the Citadel because they never bothered to look there, either with their own mystic senses or by sending minions to Lustria's far south.
The climate of Lustria's southern tip is generally cold. The First cannot function in that region for long without magical aid or lots of xiliqua root. Skinks and Sauri are unlikely to discover the Citadel by accident because they won't travel that far south in Lustria without a direct order.
Generally, the Slann and the other First have not considered the southern region of Lustria to be very important. The Great Debate could disrupt easily disrupt the status quo. The Merestar Coalition might try to reach out to the local High Elves here for an alliance while Mazdamundi's Coalition may wish to forcibly evict the High Elves there.

Type

Military, Base

Location under

Lustria