Tartarus

Tartarus (タルタロス, Tarutarosu) is a massive tower that appears each night during the Dark Hour in Persona 3. Because it "grows" out of the ground each night, the layout of the tower is assembled randomly, aside from certain key floors that never change. The tower consists of 6 blocks, where every section contains a specific Arcana's Guardian blocking anyone from climbing to the top. S.E.E.S. is formed years later in an attempt to discover the nature of the tower. This location is the only place where the player can fight shadows, except when they appear in outside locations during a Full Moon Operation.

Appearances

 * Persona 3
 * Persona 3 Manga

History
The site of Tartarus was originally that of a research facility in Port Island owned and sponsored by the Kirijo Group, performing experiments to harness the power of shadows. It was soon discovered that shadows can be used to influence time and space, so the research eventually leaned toward creating a time manipulation device. The discovery of the Fall, or the end of the world was to be the result. Following their employer's nihilistic wishes, the scientists worked on developing the Death Arcana shadow to serve as the harbinger of the phenomenon, believing that it was for the good of mankind.

However, the Fall was thwarted by Eiichiro Takeba, one of the senior scientists who opposed the move. While Death was in an incomplete state, he interrupted the experiment and dispersed Death into twelve parts before they could consume each other. The fragmented shadows went berserk, destroying the lab and everyone within it. This soon brought about a series of time-rending events: Tartarus was formed, and in turn brought about the advent of the Dark Hour.

Chaos reigns on the surrounding areas as many unassuming people turn into coffins, with all electronic and mechanical devices grinding to a sudden halt. One of the incomplete manifestations of Death would later escape from the ruins of the lab, pursued by an Anti-Shadow Weapon created by the Kirijo Group. Unable to defeat the shadow, the weapon seals it inside the mind of a young boy, who was the only survivor of a nearby car crash on the Rainbow Bridge...

To cover up the incident, the Kirijo Group rebuilds the ruined facility into Gekkoukan High School. Though mainly imprisoned during the normal time frame, shadows can still escape during the Dark Hour whenever Tartarus reforms, preying on human minds who are unprotected by coffin seals. The Kirijo Group, now led by Takeharu Kirijo, worked clandestinely during the phenomenon to find out how it can be stopped. They eventually discovered that people who can summon a Persona are the only ones who can effectively fight against the shadows. At the time however, only Takeharu's young daughter Mitsuru had the potential, and they were hard-pressed to find other people with the same ability.

Years later, a researcher named Shuji Ikutsuki was given the task of finding other youths with the potential. With the search bearing no fruit, he secretly began conducting experiments towards creating artificial Persona-users in the hope that Tartarus may be formally explored. Out of the thousands of youths summarily subjected to it, only three survived. However, they were mentally unstable and required constant doses of suppressants to keep their artificially-summoned Personae from killing them. Whether or not they were used in an exploration mission is unknown, but the three youths eventually escaped from Ikutsuki's control.

Now in high school, Mitsuru took it upon herself to help in the search for those with potential, and was able to recruit Akihiko Sanada and Shinjiro Aragaki. The Specialized Extracurricular Execution Squad (S.E.E.S.) eventually came into being. Ikutsuki was put in the Gekkoukan School Board and became the adviser of the group, officially listing it as a school club. A school-owned dormitory in Iwatodai became the S.E.E.S. homebase, and outfitted with special equipment that can remain functional even within the Dark Hour.

However, during an encounter with a wayward shadow in the back alley of Port Island, Shinjiro lost control of his Persona and a civilian casualty was incurred. He left the group ridden with guilt, resolving never to use his power again. S.E.E.S. would remain inactive until Yukari Takeba arrived, led to Port Island by a letter she got from her late father. She reluctantly joined the group when it was found that she also had the potential, but the exploration of Tartarus would not formally start until the protagonist and Junpei Iori were added to the ranks. With his unique ability to summon multiple Personae, the former is temporarily designated as the field leader while Mitsuru handles outside support and Akihiko stays behind to recover from recent injuries sustained from the first major shadow attack.

The Journey
After the Protagonist' agreement of joining SEES, Shuji Ikutsuki, the chairman would approve their investigation of Tartarus. Eventually their investigation involves a sophomore named Fuuka Yamagishi, where she is trapped inside Tartarus. As the story progress, SEES' would see Tartarus as a training ground, due to the mass number of Shadows residing inside.

It is later revealed that Tartarus was in fact, is a sign that Nyx has been called upon and it's entire existence is in order to provide a bridge for Nyx's inevitable arrival. To make matters worse, the twelve shadows SEES has defeated is actually part of Death, destined to be defeated and rejuvenate with Death.

Assuming the form of Ryoji Mochizuki, Death offers SEES two choices: Killing Ryoji, thus ending the Dark Hour and Tartarus long enough before the arrival of Nyx, or face Nyx herself. The former choice, however, erases everyone's memories regarding the Dark Hour, and thus, their memories between each other, allowing them to lead their normal lives until the arrival of Nyx. Should the protagonist chose not to kill Ryoji, Death becomes intangible within the world, and awaits SEES in the highest plane of Tartarus.

In SEES' final confrontation with Nyx, the Protagonist forged the Judgment Arcana, gaining it's strength for every floor they've traveled in the final block of Tartarus. Eventually SEES would face Jin, and Takaya, both hoping to halt SEES' advance towards Nyx. By venturing to the highest plane, Ryoji is shown serving as an avatar of Nyx, where he engages SEES. Despite SEES' assault, Nyx' avatar would shrug the damage away, lamenting that should more people are like them, perhaps the Fall could be avoided, and continue his summoning of Nyx.

The protagonist would later forge the The Universe Arcana and ascends towards the moon, where Nyx resides. The bonds he has forged with SEES and his other friends give him power to fight the sorrow, depression, and apathy of humankind, which were what drew Nyx to Earth, through the cheering of his friends, he uses the World arcana to seal Nyx away, ending the Dark Hour and Tartarus. Tartarus is last seen breaking apart, slowly turning back into Gekkoukan High School, along with the moon reverting to its original color.

The Answer
In the playable epilogue of Persona 3: FES, titled the Answer, it is revealed that the implantation of Tartarus created a cove underneath, creating the Abyss of Time. Through the sorrow, grief, and depression of SEES members after the death of the protagonist, the Abyss of Time was attracted and spread it's influence towards the dorm.

Trivia

 * In Persona 3: FES, after recruiting Fuuka, the protagonist can gain access of selecting different kinds of background music.

Blocks
Tartarus is divided into multiple "blocks", each of which has its own unique architecture. With the exception of Monad, the name of each block is taken from the seven worlds of the Quabalah.
 * Thebel Block: Floors 2-16
 * Arqa Block: Floors 17-64
 * Yabbashah Block: Floors 65-114
 * Tziah Block: Floors 115-164
 * Harabah Block: Floors 165-214
 * Adamah Block : Floors 215-263
 * Monad Depths : An extra "basement" block which consists of 10 floors.