Recent analyses were made on the crystal bottle containing the Holy Blood. The bottle has been dated as of the 11th century. It is also sure it was made in an area near Constantinople. Although in the Bible there is no explicit mention that the Blood of Christ was ever preserved, in one of the Apocryphal Gospels it is narrated that Joseph of Arimathea preserved some drops of the Blood of Christ.
According to an ancient tradition, Count Diederik van den Elzas brought the bottle containing the Blood of Christ from Jerusalem to Bruges during the second crusade. Recent investigations, however, have pointed out that the relic arrived in Bruges at a later date, probably around 1250 coming from Constantinople.
The veneration of the relic is at the origin of the internationally famous procession that is held every year through the streets of the city on the day of the Feast of the Ascension. The citizens of Bruges dress in historical customs and reenact biblical scenes and the arrival of the Count of Flanders who brought the holy relic.