Catholic believers particularly commemorate the Last Supper and the Transubstantiation of bread and wine into the Body and Blood of Jesus Christ. The Catholic Church also commemorates this event on Holy Thursday, but on that day it also remembers the Passion of Jesus Christ; the Feast of Corpus Christi, on the other hand, has a character of thanksgiving and joy. In Poland, it is celebrated on the Thursday after the Solemnity of the Holy Trinity, so it is a movable feast, always falling 60 days after Easter.
quote from Wikipedia: The Solemnity of the Most Holy Body and Blood of Christ
Procession along Starzyńskiego Street:
Procession along Jana Pawła II Street: