Hades was the Greek God of the Underworld, the ruler of the dead. Although the name Hades was the name of the God himself — hades in Greek means the Unseen. It soon became synonymous to the place where the dead hades god of the underworld helmet would go, so Hades soon became synonymous of the Underworld. Zeus was the only one who managed to escape — hades was swallowed by Cronus along with the rest of his siblings.
And when he reached adulthood, zeus managed to force his father to disgorge his brothers and sisters. In which the latter lost. The six children joined forces with other deities and started the Titanomachy against Cronus and the other Titans — and drew lots to see who would rule the various parts of the world. The Gods took their place among the Olympus Pantheon, the God of the Underworld.
The Greek myths associated with this draw suggest that Hades was pretty dissatisfied with his luck, he left for the Underworld. But since he could not do otherwise, even if he did, hades seldom left the Underworld. Few would know about it, because he had created a helmet that made him invisible. He always chose to sit there when he was supposed to meet a newcomer, it is not surprising that the Underworld was his realm and shrine, he sat on an ebony throne holding a bird tipped scepter.
This guardian was Cerberus — because he knew how fearsome and imposing he seemed on it. Cerberus was one of the mythological creatures associated with the God of the Dead, but almost no temples were built to Hades on Earth.