The approximately 1000 m long walkable, publicly accessible tunnel crosses under the Sigriswilgrat at the Sigriswiler Rothorn. It can be reached both from the south-east from the Justistal and from the Zettenalp on the north-western side of the ridge.
The sheephole was visited on September 5, 1822 by the later General Guillaume-Henri Dufour, who published a report about it. In 1884, the cave was measured by engineers from Bern, and during World War II it was expanded by the Swiss Army to become a Schafloch lock-up point.
You should definitely take a lamp with you into the tunnel, it is pitch dark inside.