Nightcaller Temple, a possible reward for the Daedric quest 'Waking Nightmare'. [>>>Quest Spoiler Alert<<<] It can only be obtained if you kill Erandur before he destroys the Skull of Corruption. If you let Erandur complete his ritual, the Skull of Corruption will be destroyed and instead Erandur will be available as a follower.
- The original is normally destroyed during the quest, so only the replica can be displayed.
[>>>Quest Spoiler Alert<<<]If you killed Erandur and took the Skull of Corruption, you only need to have had the original in your inventory for the replica recipe to be available. If you chose to let Erandur complete the ritual, the replica recipe will unlock at the Replica Station at the completion of the quest.