Tartarus (Midnightverse)

Tartarus is the deepest point of the Greco-Roman Underworld. It is where the Greco-Roman pantheon imprisons their greatest enemies such as the Titans. Tartarus is also the location of the international prison for the supernatural, Cocytus. The realm is ruled over by the Elder Gods, Tartarus, Nyx, and Erebos.

Summary
Tartarus is the deepest and darkest location within the Greco-Roman Underworld. This realm was created by the Elder God, Tartarus, to be his home but eventually became a prison realm when the Elder God, Ouranos, cast the Hekatonkaries and the Elder Cyclops after deeming them to be too monstrous. Later, the realm became a prison to the Titans after the Elder Olympians defeated them during the First Titanomachy. The five rivers of the Greek Underworld all flow into Tartarus. The most famous location in Tartarus is perhaps the cavern from which the River of Lamentation, Cocytus, flows into. The cavern is also known as Cocytus and serves as an international prison that houses extremely dangerous global figures such as Samael and Kokabiel.

Cocytus
Cocytus is an area of Tartarus in which the river Cocytus flows into. Also known as Ice Hell, this cavern is considered the deepest part of the Underworld and is primarily used to house extremely dangerous beings such as Kokabiel and Samael.

Trivia

 * It is stated that it would take an anvil nine days to fall from Earth to Tartarus.