Atlas Question - Unlocking Sockets?

I've already killed a few conquerors and secured a couple watchstone, but there's one location that doesn't have the watchstone sockets (or whatever the yellow circle is called)
how do I unlock this socketed area? (red circle/ Valdo's rest)

My google-fu failed me because i don't know wtf the sockets are called.

Thanks for your help!

P.S. When I try to run a map that's in the Valdo's Rest region, I receive a warning from the map device that reads: "The watchstone level of this atlas region is too low for any conqueror to occupy the region".
Well I can't socket a watchstone anyway to level the region up... so idk what to do.

Sockets are called citadels. And if I remember correctly, you have to run maps until they appear once you kill the boss (you dont need to spawn a conqueror).

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Serakiel wrote:

Sockets are called citadels. And if I remember correctly, you have to run maps until they appear once you kill the boss (you dont need to spawn a conqueror).

You were spot on, very next map I ran had the portal to unlock said citadel.
Thank you!