Prior to the creation of humans and Amazons, all of the gods would dwell on and oversee Earth from Olympus, hence they would be forever after also known as the "Olympians." King of the Gods Zeus would justly rule Olympus, over his siblings and children (including Ares).
After Zeus' creation of humanity and later the Amazons, Zeus' malevolent son Ares would rebel against all other gods in a jealous rage, and instigate the devastating War of the Gods, which took place on Olympus.
Growing more powerful from the violence of the godly war he had instigated, Ares fought and slayed all of the other gods as they attempted to bring him down, until only Zeus himself was left. Zeus fearlessly confronted his malevolent son in combat and wounded him, temporarily driving Ares back, off of Olympus. Before succumbing from his mortal wounds, Zeus fathered Diana (as a contingency "Godkiller" that could one day save humanity by defeating Ares) by Hippolyta, and created the protected island paradise Themyscira for the Amazons to live, hidden from the god of war. Following the war, Olympus would be left empty, with the banished Ares seemingly unable to return.
Olympus' plane is portrayed as resembling an immense mountaintop, surrounded by numerous clouds.