The Corpus Christi Festival is essentially a religious event that ranks second in importance, next to the Holy Week celebrations. It celebrates the Eucharist and its elements, particularly the Holy Host. The celebration began in the 14th century and lives up to now. It is celebrated on the Thursday after the eight day of Whitsun, which is the 7th Sunday after Easter.
During the Corpus Christi Festival, the streets of Cadiz, particularly those near the cathedral are elaborately adorned and filled with aromatic plants. The custodias (which are usually made in silver) contain the Holy Host and this is paraded throughout the city in a solemn procession of devotees who wear religious costumes.
The festival began with the nun Juliana of Liege. She had a strange vision when she began to pray. In the vision, she saw a full moon appearing, its center is darkened, as if a shadow were blocking it from view. Then, it is said that Christ himself explained the vision to her, saying that the moon symbolized all religious celebrations. However, there still was one missing – the exaltation of the presence of Christ in the Eucharist. At that time, this tenet was being debated upon.