The Pagoda of the Heavenly Mirror (天鏡の塔 Tenkyō-no-Tō) is a giant pagoda that appears in the Brilliant route of Brilliant Pagoda or Haze Castle. It is located in Devanagara, the imperial capital of Mugenri. It is where the Great Mirror was located. Not much is known about the pagoda, but it's implied that Tenkai Zuifeng knows when it was built, how many floors it has and what it signified. Tenkai also says that Tsurubami Senri really liked the Pagoda of the Heavenly Mirror.
The Pagoda of the Heavenly Mirror is, according to Suzumi Kuzu, "easily 2000
stories tall", but its exact height is unknown. It is said that the pagoda gets taller every year and provides trials to those who try to climb its interior. It is a place of great religious and cultural significance in Devanagara, and even the Imperial Emperor is permitted entry only during their coronation rite.
The Heavenly Mausoleum (天上陵 Tenjōryō) is one of the many floors of the pagoda and is where the past members of the royal bloodline are buried, enshrined and worshipped. One can talk with these past members at the mausoleum. Fujiwara no Iyozane's parents, who were killed by Ooama no Ake no Mitori in a coup d'état, are also buried here.
The Great Mirror
The Great Mirror (大鏡 Ōkagami) had the ability to put a curse on the capital that reversed left and right, ideas and ideologies for the entire city. This was how the old dynasty maintained its power by reversing the people's thoughts of rebellion into thoughts of support. Curiously, the mirror's power, at least that regarding the views of the emperors, had not been in use since the rule of the previous emperor, Fujiwara no Iyozane's father.
This is evident by the fact that many people had a poor opinion of him and a declining opinion of the past emperors, including Ooama no Ake no Mitori. It is possible that Iyozane's father was the one who stopped using the mirror's power since he was the last one to have been officially up on top of the pagoda from his coronation.