The Balm ruins are the remains of a fortified cave dwelling in the Jura Mountains, in the municipality of Balm bei Günsberg. It is that canton's only cave stronghold and one of the few in Switzerland.
The stronghold was built 20 metres high in a natural cave of about 20 metres wide and 6 metres deep.
The outer wall was provided with two doorways and some narrow windows. The wet rock face was covered with a lining wall; and the rest was a simple two-story timber construction, which is shown evident by the presence of holes into which beams were inserted. While being restored, the presently visible wall openings were distorted from their original form. At a later stage in the building of the stronghold, a fortified, inhabited house with an inside width of 3.5 metres and a length of 29 metres was erected in the forecourt. Presumably this was a defensive fortification of some farming complex.
The entrance to the stone fortress stretched over a long, partly walled rise which is partly hewn from the rock. The connection between the forecourt and the fortress itself is still only incompletely reconstructed. The present-day rise is of modern source, and only partly represents its original state.
Excavations from the years 1939 and 1941 indicate that the place had been used as a habitation since early times.
References:Saint-Georges de Boscherville Abbey is a former Benedictine abbey. It was founded in about 1113 by Guillaume de Tancarville on the site of an earlier establishment of secular canons and settled by monks from the Abbey of Saint-Evroul. The abbey church made of Caumont stone was erected from 1113 to 1140. The Norman builders aimed to have very well-lit naves and they did this by means of tall, large windows, initially made possible by a wooden ceiling, which prevented uplift, although this was replaced by a Gothic vault in the 13th century. The chapter room was built after the abbey church and dates from the last quarter of the 12th century.
The arrival of the Maurist monks in 1659, after the disasters of the Wars of Religion, helped to get the abbey back on a firmer spiritual, architectural and economic footing. They erected a large monastic building one wing of which fitted tightly around the chapter house (which was otherwise left as it was).