The grotto that we see at the entrance of the church is a representation of the place where Our Lady appeared to a 14-year-old girl in the city of Lourdes in France, in the year 1858- the Grotto of Massabielle, which was located away from the city, was used herds of pigs as shelter, but soon after 11th of February, 1858, day of the first appearance, it became a place of prayer, meeting and devotion.

Grotto built inside Fazenda santa Gertrudes Church - XIX century.

On this morning, Bernadette Soubirous, daughter of an employee of the Boly Mill, heard a sound as if it was a wind gust, as she looked to the grotto, she saw a young lady dressed in white, with a blue sash around the waist, a yellow rose in each foot and a rosary in the arms. She was the Virgin Mary. From this day to 16th of July 1858, Bernadette had 18 encounters with Her in this grotto. The virgin introduced herself as " the Immaculate Conception " and these were the words that called the attention of the ecclesiastical authorities, how could such a simple girl know this expression? Every new appearance, more and more people followed Bernadette, until one day, 25th of February, a proof was asked, the Virgin then pointed with respect to a place of the grotto and said, " Go, drink from this fountain and wash yourself in it". Bernadette started to dig in the place, but she did not find water, only dirt and she started " to drink " that dirt; at this moment the authorities took her away, however, the water started to gush out and Bernadette got rid of being imprisoned. At night, a couple approached the water with a boy that was practically dead and when bathing it in the water, the baby started to cry and " he was born again ". It was the first miracle of Lourdes. Bernadette Soubirous received the Habit from the Sisters of the Charity of Nevers and the name Sister Marie-Bernard. She died on Ash Wednesday, 1879, was beatified in 14/06/1925 and finally canonized in 08/12/1933 by Pious Pope XI. There is a curious fact about Saint Bernadette Soubirous, she was the first saint to have her photograph taken. On the day of the last appearance, 10 000 people went to the grotto, today about 5 million people visit the place, between pilgrims and tourist. In the grotto, there is a statue of the Virgin and in the pedestal it reads, in the dialect of Lourdes, " Que soy era Immaculada Conceptiou ". On the ground, to the left, a rock marks the accurate point where Bernadette knelt to pray. At the back you can see the water source found by Bernadette now canalized for taps and bathtubs. Inside of the grotto, behind the altar there is a box where people place their wishes and to the left, objects are hung to represent the received favors. The pilgrims, when arriving in Massabielle, kiss or place the hand in the rock of the grotto, thus demonstrating its faith in God, who is the rock, rock in which all can rest and construct their lives. They also drink of the water, this way answering to the order made by the virgin; and as Bernadette, they light a candle when praying and later they leave it to burn and prolong the prayer.