Mount Olympus is a kingdom in a tall mountain (it is at the top of the mountain). It is the kingdom of Zeus and he rules with Hera at his side. 12 gods live on Mount Olympus, they are Zeus, Hera, Aphrodite, Hephaestus, Apollo, Artemis, Ares, Neptune, Hermes, Athena, Demeter and Dionysus. Pluto lived in his hellish kingdom called Hades. Unlike Hades, Mount Olympus had spring clean fresh water, jewels, gold, golden palaces and statues and golden apples. Mount Olympus was like a paradise, when Hercules completed the Twelve Labors he was granted immortality and full god status by Zeus, so then Hercules took his place as the God of strength but Hercules's love for the mortal world drove him away from his throne and he went to live in the mortal world. Zeus stripped him of his godly powers leaving him only with his strength but soon Zeus allowed Hercules to regain his godly powers even though he never came back to Mount Olympus. To the human eye Mount Olympus looks like a mountain filled with clouds but it is an illusion cast by Zeus so mortals cannot detect the presence of his utopia.
The most famous representation of Mount Olympus is in the DC Universe specifically related to the Wonder Woman titles.
In the pre crisis universe of Earth 2, the Mount held the unique magical clay that Queen Hippolyte of the Amazons and Baroness Paula Von Gunther used to mold a living replica of Hippolyte's daughter Diana, so that Wonder Woman could appear to stand along side her alter ego Diana Prince at a banquet. In the precrisis of Earth 1, the Mount was attacked by the newly escaped Titans of Myth, who wanted to reclaim Olympus as their own. They were defeated after an almighty battle in its golden halls. Soon after it was attacked by Thia, the Titan goddess of the sun. After defeating the Olympians, Thia took Olympus throne until she too was defeated. At the end of the so called Crisis on infinite Earths, Olympus was not spared from attack by the Anti Monitor and the gods took up arms against the Monitors demons.
In the post crisis universe, Mount Olympus existed on a higher plane but maintained a spiritual link to the earthly mountain that bore its name. In defiance of earthly physics and gravity, structures and statuary extendeded from all directions. And the gods themselves could be seen standing at differnt angles from each other in the one room. While the gods were away from their home, Darseid ravaged the Mount and all but destroyed its temples. In his frustration that the deities were absent, Darkseid attempted to destroy the realm in an explosion. The Eternal Olympus, incapable of destruction unless the Gods themselves desired it, instantly re created itself. Although Darkseids defilment of the Mount was not washed away in the re creation, and when the gods returned they were sickened by its degradation. They decided to go on a Cosmic Migration and leave Olympus. They called forth their collective energies, boosted by Amazon prayer and destroyed Olympus before they left this plane. The cataclysm severed the deities link with the earthly Mount Olympus but gave the Olympians the power to start their exodus and the spark needed to create New Olympus.
Somewhere beyond known dimensional space, the gods created New Olympus, a fortress that mirrored their former home, but was larger and more grand than before. Like Olympus before, it was linked to other Olympian dimensions, Tartarus, the Areopagus and other realms such as Asgard and Heliopolis.
The Olympians returned to our dimension just as the witch Circe unleashed her War of the Gods. The sorceress used her boosted magical powers to trap the gods on New Olympus and disrupt communications to other realms. She transported the Roman Gods to New Olympus to battle their Greek counterparts for control. The Romans Olympus having been destroyed when the Olympians destroyed their Mount Olympus. The Olympians managed to bring their mortal champion, Wonder Woman, into the realm to help battle the Romans warrior, Captain Marvel. The conflict nearly tore apart the newly formed Olympus. With the war having repercussions on earth, with storms raging and earthquakes tearing the world of man apart. Circe moved New Olympus into earths orbit, hoping the destruction of both would reignite the universe. Superman and earths heroes took the fight to Olympus and helped turn the tide. Wonder Woman seemingly destroyed Circe and the greek Olympians joined their parents, the Titans of Myth, in roaming the universe. Leaving the Roman gods in charge of New Olympus.
Upon returning to this plane and New Olympus, the Greek Gods merged with their Roman avatars, becoming single deities once again. Zeus took his throne on Plympus once more, just as his newly awakened father Cronus attacked New Olympus and usurped him before being defeated by Wonder Woman. Shortly after that, Athena, goddess of Wisdom usurped her father and sat on Olympus throne as its Queen. Granny Goodness, an agent of Darkseid, over powered Athena and took her place, enslaving the gods, and took control of Olympus. The gods were freed by Hippolyte and returned to an Olympus once again ravaged by Darkseids forces. Zeus once again sat on Olympus throne and raised an army of heroes that he named Olympians to bring renewed worship to the gods and power to restore their once might citadel.