One of many things I hope to do next weekend while visiting family outside Philadelphia is take a trip to the so-called "Cave of Kelpius," an artificially enlarged "cave," complete with stone doorframe, on the banks of the Wissahickon.

[Images: The Cave of Kelpius, via Flickr-user veghead and U.S. History].

There, in the humidity and quiet of what is now Fairmount Park, "Philadelphia's first mystical guru came to meditate and await the Second Coming." He was called Johannes Kelpius, "and his followers arrived in newly-founded Philadelphia from Germany in 1694 and chose the wild and beautiful Wissahickon as the best place to await the millennium."

Wikipedia adds that "this belief, based on an elaborate interpretation of a passage from the biblical Book of Revelation, anticipated the advent of a heavenly kingdom somewhere in the wilderness during that year. Kelpius felt that the seventeenth-century Province of Pennsylvania, given its reputation for religious toleration at the edge of a barely settled wilderness, was the best place to be." That the heavily vegetated old valleys and hills outside Philadelphia were, at that time, wild enough to be seen as the possible site for an unnamed "heavenly kingdom" in the woods is not, in fact, all that surprising to anyone who has walked around on a particularly humid August evening, through the massive trees and rocky pathways of the region.

Oddly enough, though, this subterranean meditation chamber for a 17th-century doomsday cult—a kind of Rosicrucian NORAD in an era of breeches and buckled shoes—appears to be only a few hundred yards from the running paths on which my cross-country team practiced in high school. Yet it was something I had never heard of till a few weeks ago—probably because it's more likely a former springhouse, and not the Waco-like cave of a mystical group at all.

Nonetheless, a quick visit to the Cave of Kelpius—now in the absurd position of being ringed with suburbs—is in the cards.