Just like many places in Flanders, an Our Beloved Lady’s Lourdes-cave was also erected in Olsene. Madame Polydore Piers de Raveschoot wanted to give people from the neighbourhood a chance to honour Our Beloved Lady’s Immaculate Conception close to home. She chose the road that crosses Olsene and Machelen and also the ‘Kasteeldreef’ as the destined place. The cave that would be called ‘Olsene Rotse’ (Olsene Rock) by the people, would see its first use in 1876. Although bigger pilgrimage places and other religious heritages in Flanders would dissappear more and more, the Mary-celebration stay quite lively in places like this cave.