Grotto

A grotto is a local organized group of Satanists, as well as the regular meeting place of groups of Satanists. The term originated with the Church of Satan, founded in 1966 in San Francisco, which set up grottoes around the United States. In the mid-1970s, the grottoes were dissolved and the church was reorganized as a secret society. Other Satanist organizations also use the term grotto for their local chapters.

Source:

The Encyclopedia of Demons and Demonology – Written by Rosemary Ellen Guiley – Copyright © 2009 by Visionary Living, Inc.