The Holy Nation has a total of twenty-two layers, with the twenty-second layer being the solitary prison of the Eternal Pope; and the twenty-first layer being the residence of the Holy Maiden and her candidates, and no one would enter except for the election of the Pope.
Because the eighteenth ring is the prison of the Holy Nation. Though generally, no one would attempt a jailbreak or escape from the Holy Nation... without special permission, ordinary people can usually only enter up to the seventeenth ring at most.
The upper five layers are all forbidden zones, collectively known as the "Holy Sanctuary." This also signifies the meaning of the Pope's crown, the "Holy Crown" — from this layer onwards, entry and exit by anyone require the Pope's permission.
The nineteenth circular ring is dedicated to various major ceremonies of the Holy Nation, roughly equivalent to large halls in human society. Here, it's also called the "Near Heaven Altar" by the elves.
