In the northern French city of Dunkirk, thousands of people look forward to carnival season every year. As Mardi Gras approaches, the carnival transforms the city: the Black Cat Ball, fancy dressing and herring throwing from the town hall balcony are all part of the two-month-long festivities. The tradition dates back to the 17th century, when shipowners would host a big party for fishermen before they sailed off to Iceland for six months to fish for cod. Today, the tradition continues and is prepared weeks in advance.