ad Gadu, Domus Magna Ex Miscellanea, lies in a series of regiones centered on an island in Llynnau Cregennan in the Eryri region of northern Wales. A wooden jetty allows a ferry boat access to the island, which is otherwise edged with sheer twenty-foot cliffs. The island lies about twenty paces from the shore at its closest point, although the ferry jetty lies about 25 paces from shore.

A steep switchback path leads from the jetty to the top of the cliffs, where three stone cottages and a stable provide accomodations for visitors. Visitors are discouraged; Cad Gadu has a secretive reputation.

A white stone path starts amidst the cottages, and leads in a winding route across the island, passing between pairs of white pillars at two places along its route, which allow access to the regio. The conventum lies within the first regio layer, with sancta in the second regio layer, although other layers are reputed to exist.