The underworld a.k.a the land of the dead is where all those who died come here. It is ruled by Hades, the god of the underworld and wealth, who is the eldest brother to Poseidon and Zeus. The underworld is split into sections:

Asphodel meadows- where souls of everyday people go when they didn't achieve any recognition nor greatness.

Mourning fields- souls of those who wasted their lives for love to never come.

Elysium- where souls of heroes and demigods go to such a paradise, it's an easy afterlife for the heroes and demigods.

Tartarus- a prison beneath the underworld where those who committed grave crimes against the gods go there, it's also a prison for the titans who went to war but lost.

There are rivers that divert the areas of the underworld that only Charon, the ferryman who works for Hades, can cross via a boat. The rivers include:

Styx- the river of hatred, it's the central river that connects to other rivers.

Lethe- named after the goddess of the same name, souls of the dead drink from the river in order to forget their past lives in order to undergo reincarnation.

Acheron- the river of pain, charon comes to when the souls of the dead awaits for their destination.

Phlegethon- the river of fire, it leads to the depths of tartarus.

Cocytus- the river of wailing

Oceanus- named after the titan of the seas, the river encircles the world and it marks the east edge of the underworld.

There are three judges that judged the souls to where their destination is located, the following judges include:

Minos- the king of Crete now turned judge, he is the main judge that does the deciding vote.

Rhadamanthus- the brother of minos now turned judge, he judges those who are qualified for Elysium.

Aeacus- once a king of an island turned judge, he's also the guardian of keys.

Thanatos works with hades as part of his punishment for the crime for joining the titans. After losing his physical form, he either travels throughout the world carrying out his job as the god of death or staying within Hades palace.

Cerberus is the guardian of the entrance to the underworld, his job is to prevent the souls from leaving.