A temple to the left of the Vifrost Bridge. It is where the high priests and masters of each class reside.
To find this Place in-game, use /where Great Temple of PandaemoniumA magical birdie will appear somewhere near you and will guide you to your destination.
This Place is a quest hub in the Pandaemonium Quest Series.
The 4 Masters of the archetypes are here, as is the High Priest, Balder. This is where you go for A Ceremony in Pandaemonium.