Each year on Ascension Day, thousands of Portuguese citizens travel from Niederwiltz to the shrine of Our Lady of Fatima to celebrate mass.

The shrine was set up on "Op Baessent" hill in 1952 after a group of Wiltz inhabitants made a promise during the Second World War. Taking refuge in a cellar in Wiltz, victims of the atrocities of war, they promised each other, on the evening of 13 January 1945, to erect a shrine dedicated to the Sacred Heart of Jesus and Our Lady of Fatima.

The first official pilgrimage of Portuguese families took place in 1968 in Wiltz. Since that day, the spotlight always falls on "Op Baessent" on Ascension Thursday and the streets of Wiltz are filled with believers.