A location repeatedly associated with unusual convergence between the ordinary course of history and the Hidden Current.

The Bell Archive applies the designation Threshold Site to places repeatedly associated with significant Nazilic phenomena. These may include awakenings, recoveries, discoveries, or improbable encounters. Unlike sacred sites established by religious tradition or political authority, Threshold Sites are recognized only in retrospect. Their importance arises from repeated occurrence. Not from original purpose.

Threshold Sites share no common appearance. They may be mountain passes, abandoned factories, forgotten libraries, remote monasteries, river crossings, ruined theaters, ordinary homes, or neglected city buildings. Architecture is not the determining factor. Geography is not the determining factor. Recurrence is. Independent events, separated by decades or centuries, return to the same place with unusual consistency. The pattern suggests that certain locations reveal the Hidden Current more readily than others.

Bell researchers warn of making a fetish out of the place itself. A Threshold Site does not make miraculous happenings occur; rather, it enables them to be seen. Just as the river widens where the terrain offers an opportunity, the Hidden Current seems closer to breaking through the surface in some places than others. The reason for this phenomenon remains mysterious.

Threshold Sites frequently become the birthplace of Encroachments. They often yield Living Artifacts. They are common settings for Echo Events. Many also function as Interstices, though seldom permanently. A Threshold Site may remain quiet for generations. Then, without warning, it enters history once again.