Heliopolis

Heliopolis was a plane that across cosmologies was considered the home for a number of deities within the Pharaonic and Mulhorandi pantheons.

Cosmography
Under the Great Wheel model, Heliopolis was said to be a single divine realm that resided on Buxenus, the second layer of the plane of Arcadia. Jointly ruled by Ra, Isis, Osiris, and Horus (later Horus-Re after his Ra's death). While under the World Tree model, it was considered to be one of the Neutral Planes that were connected to the World Tree and the home of all members of the Mulhorandi pantheon.

Great Wheel
Under the Great Wheel cosmology, this realm was said to be an immense burning desert of bright sand that was laid out like a triangle, divided into three equally sized domains. It was touched at every corner by a scorching sun, which was guided across the sky by Ra's solar barge Manjet. This was in contrast to the rest of Arcadia, which received light from the Orb of Day and Night, though the time of day for both coincided. When the time for day to end came Ra's barge became a funeral barge, referred to as Mesketet, and briefly provided light to the realm of Osiris.

Whenever the sun faded in Heliopolis the temperature would drop dramatically. However, the overall temperature varied between the three domains that each deity governed. The domain of Ra was the hottest of three, the heat striking even indoors and in shadowed area. Fauna were almost never seen out during the day in his realm, due to the unbearable heat of the sun. The valley that Osiris presided over was the coolest of the three, even when standing beneath the sun. And the sloping domain of Isis between them was moderate in temperature. With its moderate temperature, this domain was where all wildlife and most plants were found, being spread over with thick grass and dotted with fig and palm trees.

Creatures that were known to inhabit Heliopolis included lions, camels, serpents, and scorpions.

Great Wheel
Ra and Osiris were considered to be the dominant powers of Heliopolis, while Isis and Horus held secondary realms. They shared the role of leader depending upon what pressing business they had to attend to. Horus wandered between all three realms, rather than having a realm of his own, at least up until his change in station.

The Great Wheel model also claimed Heliopolis to once be home to the Pharaonic deities Set, Geb, and Nut. The former was banished for his transgressions, while the latter two chose to leave after the god Shu forbade their marriage.
 * Thekele-Re, the First Realm of Heliopolis, was the domain of Ra. Following the death of Ra's Mulhorandi incarnation Re, his son Horus received both his powers and divine realm, taking up the new name of Horus-Re.
 * Gizekhtet, the Second Realm of Heliopolis, was the domain of Isis.
 * Memphiria, the Third Realm of Heliopolis, was the domain of Osiris.

Inhabitants
Besides petitioners, undead of good alignment could be found wandering the valley of Osiris and they were treated as no different from the living by the realm's petitioners.

Rumors & Legends
Some legends claimed that the great serpent Apep was buried beneath the sands of Heliopolis.