Good Friday is a unique and uniquely solemn day in the Christian calendar. Celebrated the Friday before Easter, it commemorates the crucifixion and death of Jesus. This year it will fall on April 3 for Catholics and Protestants, and April 10 for Orthodox Christians. Across Christian denominations, worship service on Good Friday is unlike those on most other days. For Catholics, it’s the only day when Mass is not celebrated. Instead, the services on Good Friday include centuries-old, once-a-year traditions both during the liturgy and out in the streets, where elaborate processions and other rituals of fervent popular piety are held in many countries.