Lourdes, France, Aug 16, 2016 / 11:15 am (CNA/EWTN News).- The popular pilgrimage site at Lourdes, France beefed up its security Monday for the Solemnity of the Assumption. About 500 security force members were present, along with patrol dogs, according to the BBC, which reported that around 25,000 pilgrims visited Lourdes for the Marian feast day.

Dogmatically defined in 1950, the Assumption celebrates Mary, the mother of Jesus, being assumed into heaven, body and soul, when her earthly life was complete. It is celebrated on August 15 each year. The increased security came amid heightened vigilance after a string of terrorist attacks in France.

On July 26, French priest Fr. Jaques Hamel was killed when two armed gunmen stormed a church in the Normandy region. They slit Fr. Hamel’s throat as he celebrated Mass. ISIS claimed responsibility for the murder. Other attacks have also taken place in France during recent months, including the Nov. 13, 2015 series of bombings in Paris that claimed more than 100 lives, and the July 14, 2016 truck attack that killed 84 in Nice.

Lourdes is one of the most well-known pilgrimage destinations in the world following a series of Marian apparitions in 1858 in which the Virgin Mary appeared to a 14-year-old peasant girl named Bernadette Soubirous. In the apparitions, Mary confirmed her identity as “the Immaculate Conception.” The apparitions were approved by Pope Pius IX in 1862.

Millions of pilgrims flock to the shrine each year to visit the grotto where Mary appeared to Bernadette, who is now a canonized saint. Pilgrims take water from a spring Bernadette dug at Mary’s request. The shrine’s waters have resulted in various types of healing for those who drink it or are immersed in it.