Orthorbbae is the place where young nobles and children of rich commoners come to study. Orthorbbae is a school for magic in Chel'el'Sussoloth. Admittance is not limited to nobility, and any Drow parent or guardian capable of funding their child's education may have him or her educated in the compound. Study is not limited to magic but includes basics in math, history, mana and natural sciences, and combat.
Orthorbbae started as the original settlement building and fortress in Chel'el'Sussoloth. It's structure is reminiscent of the original worship of both the Moons, the Gods of the surface, and Sharess. The ceiling of the cavern contains a beautiful magical fresco of what the heavens possibly looked like in the Moons Age, before the Great War that drove the Dark Elves underground. As elves branched out and conquered the Chel'el'Sussoloth cavern, Orthorbbae was transformed into a neutral ground where the young of all the clans could be educated. Due to its former roll in the past of being a fortress and it's separation from the rest of the cavern via only a few entrances, the facility is difficult to gain access to when locked down. During the Nidra'chaal War the Orthorbbae was in a semi-locked-down state in order to protect the children of the clans studying there from coming under attack in the main battle with the Sharen. However, previous to the war the Nidra'chaal gained access to the compound secretly and attacked students and teachers there, forcibly tainting many. How they gained access is unknown, but may be a sign that the fortress has weak points.
Currently, Snadhya'runes Vel'Sharen is Headmistress of Orthorbbae and the Crescent, having taken the place of the demoted former headmistress, Sha'sana. While each Leg has its own Headmaster, Ashu'athama Sharen appears to head all meetings between them. Valla'drielle Val'Kyorl'solenurn is Headmistress of the Drowussu School.
The compound is divided into four regions: the Dome in the center, the Crescent (surrounds the Dome in a crescent shape) for females, the Legs (eight towers) for males, and a separate school for the Drowussu of the Val'Kyorl'solenurn. It's overall appearance is an eight-spoke wheel with a curved building attached to the central portion at the front. It was previously described to look like a spider, but now only seems so in an abstract sense.
The Main Hall of the Crescent is a lavish common area. Along its walls are hallways and doors connecting to dormitories and classrooms. In the central region of the hall is a large white statue of the Goddess, Sharess, surrounded by statues of the Nine Clans' animal symbols, set in the center of a pool. The statue is many stories high and is illuminated from above from a round window. It gives an atmosphere of wealth and power to the Crescent.
The crescent of the Orthorbbae is the female school and quarters. The Crescent is connected to the Legs via the first levels of each tower and the lower basement levels. Males are prohibited from entering the Crescent unless they were unfortunate enough to be caught and used as guinea pigs for girl's classes. Girls must change roommates every so often, as a rule.
The building is shaped like a crescent moon and encircles the Orthorbbae dome interior to the Legs. Inside houses the female dormitories and classrooms, and most likely small libraries and a cafeteria. Female instructors and the Headmistress also live inside the Crescent.
The Drowussu School
Separate from the other buildings in the cavern resides the Kyorl'solenurn school. It is depicted in the manga as a step pyramid-like building with the traditional vertical eye clan symbol. In this building only Drowussu of the Kyorl'solenurn clan train in their future clan roles. While in the protected Orthorbbae cavern, the School appears to be a miniature fortress of its own.
Not much is known about the Drowussu school. In Chapter 10 Chirinide Val'Kyorl'solenurn goes to this building to retrieve her Blade, Templar-in-training Shan'naal Kyorl'solenurn, to accompany her in her quest to the surface. While the exterior in Chapter 2 is dark and blends in with the cavern walls, the interior appears light and colored in the black-and-white Clan colors. It is assumed that there are dormitories for the students and teachers, and there are classrooms (one is seen in Chapter 10). Libraries, cafeterias, training areas, and common rooms are also likely.
Both male and female Kyorl'solenurn go to this school, though gender division beyond classes for particular roles (such as Templars or Wardens) is unknown.
The Eight Towers
Each tower is made up of 27 levels, if they all are similar to Davya. All levels are connected to each other via a tube which can only be navigated by floaters (for students and teachers) or levitation. The only exception to this is the second floor's trap door for movement of goods and any floor connected to another tower or the Dome.
The male section of the school are called the Towers, of which there are eight:
Devya, the First tower of Orthorbbae. Its headmaster is Ashu'athama Val'Sharen.
Divya, the Second tower of Orthorbbae.
Dravya, the Third tower of Orthorbbae.
Druva, the Fourth tower of Orthorbbae, connected to Davya by a bridge from the hub at the tenth floor.
Davya, the Fifth tower of Orthorbbae, where Ariel went for schooling under the watchful eyes of her brother Kelnoz Val'Sarghress, the current Headmaster of Davya.
Danava, the Sixth tower of Orthorbbae, connected to Davya by a bridge from the hub at the tenth floor.
Darvan, the Seventh tower of Orthorbbae.
Dravyd, the Eighth tower of Orthorbbae. Its headmaster is Jhin'elam Illhar'dro.
First level This level contains an entrance and a connection bridge to the central buildings of Orthorbbae, including the Crescent. Boys of the towers are forbidden to use this bridge, possibly because it connects straight to the Crescent. Access straight to the Dome is higher up.
Second level Storage area. This is the only floor that is noted for being connected to a lower one in a way other than the central tube. The trap door is for movement of goods to be stored.
Third Level The cafeteria level. May have some connection to the second floor for easier access to food stuffs, but was not mentioned in Ariel's tutorial (due to possible unimportance to the students).
Fourth Level Small library. There is a larger one in the Dome, so this may just contain basics for newer students.
Fifth through Ninth Levels Classrooms, two per level.
Tenth Level Connecting floor. Contains bridges to the towers on either side of the tower in question (so the fourth and sixth towers, Druva and Danava, in the case of Davya). Also contains a connection point straight to the Dome which males are allowed to use.
Eleventh through Twentieth Levels Student quarters. There are eight rooms and one communal restroom per level. Each student lives on their level for two years before moving up to the next, which makes the average stay in the Legs of Ortorbbae twenty years.
Twenty First through Twenty Fifth Master Quarters, two per level.
Twenty Sixth Headmaster quarters, entire level.
Twenty Seventh Empty Level. A door appears to exist there, but it supposedly leads nowhere (or at least there's no common knowledge of where).
Lower Levels There are levels below the first floor that are forbidden for male students to enter. They may be connected to the Crescent and therefore entry is limited to female students. Males found in this level (whether due to curiosity or falling down the tube) are fair game for females to use as guinea pigs in experiments.
The Ninth Tower
Rumor has circulated among students for centuries of a mysterious ninth tower that exists somewhere on the premises. This tower actually exists, but its location is only known to a scant few: The former headmistress Sha'sana, the current headmistress Snadhya'rune Vel'Sharen and her protector twin Khaless, and Sil'lice who made Chrys'tel aware of its presence in order to seek the truth of the Nidraa'chal War.
This article reflects events up to chapter 39.