SEVILLE, Spain — Each spring, for one week, Seville transforms. The scent of orange blossoms mixes with heady incense. Booming drums and soaring brass bands echo down narrow streets. Gilded floats topped with life-like statues and vibrant floral arrangements are carried across cobblestones in elaborate processions. These parades unite pageantry, penance and tradition in a display so beautiful that it touches the hearts, even of those who don't believe in their underlying message. This is Seville's Holy Week, known as Semana Santa. From Palm Sunday to Easter Sunday, the city's historic center strains at the seams. People bus in from...