The Stone Sprite City

Not even the bustling hub of Stonewall could compare to these stone walls, which seemed to sink into the very depths of the land.

— Marcus Pfieffer

While the architecture of Zenxon consists primarily of a contrast between wooden sprite-built structures and stone human-built structures, there is one stone city in northern Zenxon which was built before humans arrived on the island. The name of the city is unknown, though it has become a common tourist destination. It is best known for its appearance in the Journal of Marcus Pfieffer, who is typically credited with its re-discovery.
From the ruins, archaeologists have determined that the city was, at one time, a thriving, self-sufficient haven in the woods. Based on the deterioration of the ruins, the overgrowth of the area, and the stylistic differences, most believe it was build before humans set foot on the island. Its distance from other Sprite towns indicates the residents had little, if any, contact with other sprites. Until recently, there was no paved road to the ruins, though it could be reached by trails that may have been formed by hunters.
The most curious part of the city, however, is an an elaborate series of underground tunnels. Hidden trap doors have been found in several of the ruined buildings which lead to these tunnels. The tunnels themselves, however, extend beyond the limits of the city above, and contain large enough chambers for a second city underneath the first. Though few artifacts of the city's creators have been found, more recent artifacts, including scraps of journals, indicate the city was used as a hiding place for sprites and wizards during Zenxon's anti-magic pogroms. Some skeletal remains have been found in the underground chambers, but archaeologists believe these to be from these later groups, rather than the original builders, who seemed to bury their dead in the nearby mounds.
No one knows who built the city or what happened to them. The leading theory is that it was built by a sprite cult that purposely isolated themselves from other sprite settlements to avoid religious and cultural conflict. This would explain the difference in building in stone, rather than the typical wooden structures that comprise other sprite settlements. The tunnel system is believed to be built for religious purposes. Their isolation, however, is likely what lead to their deaths, from a mixture of weak genetics and disease. Some Astromythologists have instead posited that the city was built by people visiting from the Homeworld, who hoped to watch Nideon.