The grotto where the apparitions occurred is actually a 10m-deep by 10m-wide crevice in a boulder (Massabielle) by a stream. A Madonna in Carrara marble, sculpted by Fabisch in 1864, marks the exact spot of the apparitions. The spring that Bernadette made flow on 25 February 1858 is still visible at the back of the grotto; an underground waterway channels the water to fountains to the left of the grotto and to pools downstream into which the pilgrims are plunged with the help of hospital staff.