Tomb of the Raven Queen
Entry into the crypt involved a long battle and interactions with a mural-covered magical-and-now-shattered-after-being-turned-into-ice door.
Discovered by the party while trying to get into the tower of House Nocturne. Consists of multiple passageways, smaller side rooms. Seemed to have been largely left alone for a very long time.
The party finds a room which appears to have been looted.