Mount Olympus
Yggdrasil and Mount Olympus are two astral landmarks that are normally encountered by travelers from worlds that worship the Norse and Greek pantheons, respectively, but travelers from other Prime Material planes can encounter them. Both are longstanding conduits from the outer planes to Alternate Prime planes. They were each created by a group of Demi-, Lesser, and Greater Powers and worshipers in the Prime Material plane.
Mount Olympus is a huge mountain that links the Greek pantheon's part of the plane of Olympus with the Prime planes that they are strong in. It has exits on the lower layers of the planes of Gehenna, Hades, and Tarterus. The mountain is a solid and permanent conduit that weathers the waxing and waning of faiths in the Prime Material and the fortunes of the gods in the outer planes. The traveler is confronted by a mountain wall rising from the mist of the Astral Plane and disappearing far into the distance. The traveler can then climb the mountain to the appropriate outer plane, descend to the reachable lower planes, or explore the alternate Primes that the conduits touch upon.
At the true terminus (reached after the standard amount of travel time), the mountain ends in a color pool similar to that of a fixed portal. The traveler can then pass into the outer plane as if moving into an alternate Prime Material or the Astral plane. Yggdrasil and Mount Olympus are the best-known of the permanent conduits that link the outer planes with Prime planes and with other nonlinear outer planes.
The Greek pantheon is a fractured group yet they have gathered together into a common front on at least two occasions: once to defeat the great titans and cast the majority of them into Tarterus, and the second time to fashion Mount Olympus as a continuous conduit that reaches from the plane of Olympus through the Astral Plane and into Hades, touching all of the Prime planes where the Greek gods are known. It is not certain that the Olympian gods forged this mountain; others claim that the Olympians are little more than inheritors and usurpers of a conduit that existed since before the titans ruled Olympus. Whatever the case, the gods of the Greek pantheon have remained together in the same location, at the head of the mountain, for mutual benefit and defense. The lair of Ares is a massive battlement near the portal to the Mount Olympus passage, mirroring that of Athena, who dwells in a palace on the far side of that portal.
The upper layer of Tarterus was once linked (via Mount Olympus) to the third layer of Hades, the first layer of Olympus, and the various alternate Prime Material planes where the Greek and titan pantheons were worshiped. Mount Olympus met the upper layer of Tarterus at Mount Othrys, and it was to here that the titans retreated upon their defeat. The Powers of Olympus used their combined might to shatter the part of Mount Olympus that reached this plane, trapping the titans in Tarterus.
