The Mournhold Temple was the home of Almalexia, one of the god-kings of Morrowind. The temple served as the main place of worship for the Tribunal and the administrative main location for the Tribunal Temple.
During the time of the Planemeld, the temple had many relics from the three different races of the Ebonheart Pact. In 2E 582, the temple was invaded by Daedra summoned by the Maulborn for a plot to overthrow the Tribunal and return the Dunmer back to worshipping the Daedra. The invaders were eventually repulsed by the Vestige, who at the request of Almalexia used the power of the tribunal to kill the invaders.
The temple survived the destruction of Mournhold during the Accession War, and the populations disillusionment with the Tribunal following the Red Year. Around two hundred years, the last vestiges of Almalexia were being removed from the temple by the New Temple. In 4E 201, the New Temple added a new sanctuary and House Indoril had to erect a large building in the Plaza Brindisi Dorom to house the many priests and pilgrims that came to visit.