Underworld

The Underworld is located under DOA Recording Studios in Los Angeles, California. It's where the souls of the dead go when they die. The Underworld is divided into various sections. The Judges of the Underworld decide where a soul should go based upon their life's accomplishments.

Entrance
The entrance is managed by Charon, the reaper of souls. He takes them into an elevator and heads down, where they sail across the River Styx toward the opposite shore. On that shore, Cerberus stands guard. The souls must pass by Cerberus toward their afterlife.

A lesser-known entrance stands in Central Park, NY. Orpheus created it to retrieve the dead spirit of his wife. Music is required to open this door and Percy and Nico used it in The Last Olympian. It lets out behind the main gates, therefore being more direct to Hades' palace.

The Fields of Punishment
The Fields of Punishment are fields of complete and brutal torture for souls of people who have done extreme wrongs in their lifetimes, one of them being the mortal Sisyphus who cheated death numerous times and tricked Persephone. It has "miles of barbed wire separating the different torture areas." Some of the torture areas include being burned at the stake, running through cactus patches forever, or being forced to listen to opera music for eternity.

The Asphodel Fields
Souls who don't wish to be judged go the Asphodel Fields. According to Grover, it is described as "standing in a wheat field in Kansas for eternity." Annabeth Chase stated that most people don't do either good or bad in their lifetimes, thus floating in the Asphodel Fields forever.

Elysium
Elysium is the place of paradise for heroes. Those who die a hero's death live in peace in Elysium. Percy states that is where he wants to end up and it is where the demigod and ex-Hunter, Bianca di Angelo is now. Charles Beckendorf, Silena Beauregard, Michael Yew, Ethan Nakamura, and Luke Castellan are also there.

According to Percy, the only part of Elysium that can be seen behind its locked gate are several houses from different time periods. The grass ripples in rainbow colors and it is possible for one standing outside the gate to hear laughter and smell barbecue cooking.

Isles of the Blest
The Isles of Blest is reserved for heroes who have chosen to be reborn three times, each time achieving Elysium. Not many people live in the Isles of the Blest, and not many will, as there are not a lot of people who do good in their life, according to Percy Jackson. Luke Castellan, was one of the few heros who wished to go into the Isles of the Blest, when he killed himself in order to destroy Kronos. Annabeth instead, tells him that he always put too much stress on himself.

It is described as a glittering blue lake with three small islands with a vacation resort in the Bahamas.

Hades' Palace
Hades' palace is where he lives and operates his command over the Underworld. His gate is engraved with images of death and his throne is made of bones, with a flowery throne next to it for his wife, Persephone.