Hades' Palace

Hades' Palace is located in the Underworld and is the home of Hades, god of the Underworld and his wife, Persephone, the goddess of Springtime, flowers, and young life.

Description
It is modeled after Mount Olympus, since he is not welcome there for the most of the year, unless it's the Winter Solstice. It is black and bronze, while everything in Olympus is silver and white. A person can only reach the palace if Hades wishes them to. If he doesn't, the person will just keep walking for eternity without ever reaching it. In front of it is Persephone's garden, which has been said to be one of the most beautiful gardens on Earth.

Known Rooms

 * The Throne Room – Hades sits upon a black onyx throne made of skulls, surrounded by dead U.S. revolutionary soldiers, British Redcoats, Greek Warriors, Roman Legionnaires, Modern U.S. soldiers, and Confederate soldiers (as security). He is also surrounded by hellhounds.
 * The Dungeon – Hades imprisons Percy here in The Last Olympian. The cells do not have any doors or windows and apparently no source of oxygen for living prisoners.

The Lightning Thief
Percy Jackson, Annabeth Chase, and Grover Underwood visit to diplomatically ask Hades to give them Zeus' stolen Master Bolt. Hades is found sitting on his throne, facing away from the three heroes. They later make a hasty retreat using Poseidon's Pearls.

The Sword of Hades
Thalia, Nico and Percy are summoned to the palace by Persephone to retrive Hades's Sword which was stolen by Ethan Nakamura. They are first summoned to Persephone's Garden then they are brought to a veranda overlooking the garden.

The Last Olympian
When Percy Jackson goes to the Underworld with Nico di Angelo to bathe in the River Styx, Nico reveals that he had tricked Percy to get information from Hades about Nico's past and mother. He hands Percy over to the Furies, who take Percy to the dungeon, a place below the palace. The dungeon is guarded by ghostly warriors and other dead. Percy is held there for a short time until Nico shows up to rescue him. They escape from the dungeon, and make their way to the River Styx so that Percy can bathe in it and gain the Curse of Achilles.

Trivia

 * Percy dreamed about and visited the palace three times in the series: The Lightning Thief, The Demigod Files, and The Last Olympian.