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. Hades built it to resemble Olympus even though everything is black and bronze and on Olympus, everything is silver and white. There are rooms in the Palace made for his Demigod.



Hades' Palace
( http://camphalfblood.wikia.com/wiki/Hades'_Palace )

The enormous palace was modeled after Mount Olympus, as Hades is not welcomed there except on the Winter Solstice. It is made of glittering black obsidian, with a black marble portico, and the entry hall had a polished bronze floor. When Percy compared Hades' palace to Olympus, he noted that the former was black and bronze, while everything in the latter glittered silver and white.

it was mentioned that the palace had entire rooms made of gold and silver, since Hades is also the God of Wealth, with access to all the riches under the earth.

In front of the palace is Persephone's Garden, which has been said to be one of the most beautiful gardens on Earth. A person can only reach the palace if Hades wishes them to. If he does not, the person will just keep walking for eternity without ever reaching it.

You must go through Persephone's Garden before entering the Palace due to the Garden being at the front.