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Thousands pack the main square in Pamplona, Spain for the annual 'running of the bulls' festival

Alvaro Barrientos / AP

Revelers hold up traditional red neckties as tens of thousands of people packed Pamplona's main square in Pamplona, Spain, Wednesday, July 6, 2011, to celebrate the start of Spain's most famous bull-running festival with the annual launch of the "chupinazo" rocket. Perhaps best glorified by Ernest Hemingway's 1926 novel "The Sun Also Rises," the San Fermin festival is known around the world for the daily running of the bulls.

Alvaro Barrientos / AP

Revelers react as water is thrown from a balcony during the 'Chupinazo', the official opening of the San Fermin fiestas in Pamplona, July 6, 2011. The fiestas 'Los San Fermines' held since 1591, attracts tens of thousands of foreign visitors each year for nine days of revelry, morning bull-runs and afternoon bullfights.

 Later today, we'll publish more images in a slideshow from the events.