Beneath the rest of the Underworld lies Tartarus, the great cosmic pits.
Gates of Tartarus: Tartarus is secured primarily by the Triple Wall of Bronze, which extends far below the surface of the Underworld. Accessing the Pits of Tartarus is achieved by passing through one of the gates. Typically, no one just walks through the Gates without Hades knowing of it.
Night’s Apartments: The Apartments of Nyx reside just above the Pits, where the Primordial can observe the goings-on. Hades installed a thick glass wall that Nyx can cover or open at her leisure with lava rock. The Night’s Apartments stretch a third of the way over the Pits.
Pits of Tartarus: Through one gate, the open Pits of Tartarus can be reached. The Pits is where the souls of the wicked are condemned by a Judge of the Dead live for a period of enforced purgatory. If the soul is unredeemable, eternal damnation awaits them here.
Tartarus Correctional Facility: The second gate leads to the Tartarus Correctional Facility, a gloomy, storm-wracked security prison that houses the most powerful of the Pantheon’s criminals. It is guarded by the hundred-handed Hecatonchire giants, the primary wardens of the Titans, alongside a few tricks that Zeus and Hades added.