Arborea is called Olympus by primes who've heard of some of the local powers, and Arvandor by prime elves who revere a few other powers that live here. 'Course, they've both got it wrong, but whatever a sod calls this plane, the best way to sum it up in one word is to say "boisterous." This is the home of a pantheon of gods that call themselves "Greek" - a tag that reflects one of their favorite prime-material worlds. Wherever that world is, it must be a wild one because this pantheon is half-barmy with the party lifestyle. Their passions run high and deep, and the plane reflects that with stupendously craggy mountains, unbelievably deep gorges, forests of monstrously huge trees, and vast wild stretches of wheat fields, orchards, and arbors.
The petitioners who live here are a hearty lot of back-slapping, wide-grinning, epic-singing bravos when they're happy. But they drink to excess and wail like banshees when they're sorrowful. When angered, they leap into battle without a moment's hesitation (though their "combats" are better called "brawls" - lots of heads get thumped, but people seldom die). A swashbuckling cutter feels right at home on this plane. There's always hunts and battles, contests of strength and derring-do, and long, loud parties - it ain't ever dull around here!
The elven pantheon also makes its home on this plane, but it remains separate from the Greek gods. The elf gods are a bit more elegant in their behavior, though no less passionate. The petitioners pour out their joys and sorrows in achingly beautiful music, their rage in hard-eyed, cold-blooded vengeance.
The Sensates maintain a palace on this plane. It's a rambling structure of white marble, filled with sumptuous viands, beautiful art work, excellent musicians, and graceful dancers and acrobats.
Portals between the layers of Arborea are rarer than on most other planes, and those few are well guarded by the powers and petitioners, sometimes even with stone walls and iron gates. The idea isn't to keep travelers out, but to stop or slow the influx of unintelligent or dangerous monsters.
Note: Arborea originally appeared in this form in the Planescape AD&D campaign setting from TSR. Its use here is for the purposes of providing context for the campaign only.