The most important religious and popular festa on the calendar takes place on the second Thursday in January. Dressed in traditional white garb and strings of beads, Bahianas lead an 8-kilometer (5-mile) procession of similarly white-attired and perfumed devotees and partyers from Comércio to the Igreja do Bonfim [1] for the washing (lavagem) of the church steps.
The festa honors Senhor do Bonfim (associated with the important orixá Oxalá, whose color is white). After the crowd is doused with blessed water and perfume, the party really gets going, lasting long into the night.
Links:
[1] http://www.moon.com/destinations/brazil/bahia/salvador/sights/bonfim/igreja-do-bonfim