Some call it Carnival. Others, Fat Tuesay. Most Americans, however, know today's celebration by its French name: Mardi Gras. The annual New Orleans bacchanal will reach its ostentatious climax in the French Quarter this evening. But Mardi Gras isn't just a Louisiana affair. People in cities all over the world are celebrating the occasion, from Rio de Janeiro and Sydney to Venice and Cologne. We've collected some of the best images from this international event.