Remains of rock-hewn churches may be found in several European and Middle-Eastern landscapes, where natural caves and calciferous rocks invited hermits to shelter in solitude and prayer. In France, such churches were common in Aquitaine.
Full alike of dignity and courtesy, Martin of Tours kept up the position of a bishop properly, yet in such a way as not to lay aside the objects and virtues of a monk. Accordingly, he made use, for some time, of the cell connected with the church but afterwards, when he felt it impossible to tolerate the disturbance caused by the numbers of those visiting it, he established a monastery for himself about two miles outside the city. This spot was so secret and retired that he enjoyed in it the solitude of a hermit.
Sulpicius, Vita, X – translation from Sulpicius Severus: On the Life of St. Martin. Translation and Notes by Alexander Roberts. In A Select Library of Nicene and Post-Nicene Fathers of the Christian Church, New York, 1894.
Read more from source: Rock-Carved Churches in France – Medieval Histories