Ceoluua

A massive mountain in Western Xaishre. By all accounts, it shouldn't exist, and there is no known explanation of how it came to be other than otherworldly influence or divine will. it is surrounded by only a few smaller mountains, ruling out tectonic shifts, and it is not known to be a volcano, as it has never erupted and all the rock appears to be sedimentary. 
One massive city is built in a ring shape surrounding its entire base. The city also goes by the name Ceoluua. It is multicultural, with many different people living in different districts. Some do not like each other, but all respect the mountain. The city has one outer wall and one inner wall. Most outsiders are allowed through the outer wall into the city, but only select officials are allowed through the inner wall to the base of the mountain.
There is a point on the mountain where it becomes nearly unclimbable without magical help above this point lives one of the 2 tribes of green elves still remaining on Enmilon, the other living in the underground jungle of Tng'kung'kah in the Underdark. Further up the mountain, in the ice ring, lie many snow elf cities. The cap of the mountain is so far above the clouds, that no water or vegetation exists naturally there. It is one of the most desolate places in all of Enmilon, with only a few eccentric wizards living there in near total isolation. It is however high enough that it pierces the Coexistent Barrier into the Plane of Air, meaning the occasional Air native can be found there as well. The only effective way to or from Ceoluua's cap is teleportation magic. Some even elect to plane shift to the Plane of Air and fly to the cap, as most consider it easier than climbing the mountain, and faster than flying there from the ground.