Elysium

Elysium is the part of the Underworld where demigods, gods and humans go if they die, died a hero's death and/or had a good life.

It is a small section of the Underworld (compared to the Fields of Asphodel or even the Fields of Punishment) and surrounds a lake containing the Isles of the Blest. If a hero chooses to be reborn three times and reaches Elysium each time, they are invited to the Isles of the Blest (Which Percy calls the "Ultimate Party Headquarters" for the good).

It is like a gated community, with golden gates, and laughter inside. One can smell barbecue cooking from inside.

Souls can only go to Elysium when they go to the council. Most souls don't want to take that risk and just go to the Fields of Asphodel.

The Lightning Thief
When entering the underworld for the first time, Percy sees Elysium in the distance.