While his actual saint day is September 25th, the annual festivities honoring San Fermín, Pamplona's son-turned-martyr, get started on July 6th with the inaugural "txupinazo." When this rocket blasts off from the balcony of the Ayuntamiento (City Hall) to announce the official commencement of the festival, the deafening cheers and rain of champagne corks pretty much set the raucous tone for the rest of the week! 
The most characteristic part of Los Sanfermines is the daily "encierro," better known internationally as the infamous Running of the Bulls. If you intend to get a good viewing spot for the mayhem, arrive early as a crowd already starts to form over an hour before the big event. Two great vantage points are Plaza Santo Domingo, where the encierro gets started, or the wall leading up to the bullring, where the encierro ends.
The Running of the Bulls and thousands of runners, predominantly young men, dashing down an 830-meter stretch of narrow streets donning traditional white outfits and red sashes. Two rockets are launched to announce the beginning of the event; the first rocket signals that the bulls have been released, and the second signals that all of the bulls are out and running. The objective is to run alongside and touch the bulls or hit them with a rolled-up newspaper while trying to avoid any unpleasant outcomes, namely those involving horns.
After the daily Running of the Bulls, the days are full of markets, fairs, music bands and parades. The most important parade is held on July 7th, when - after the Running of the Bulls, of course - a procession dating back centuries winds through the city, accompanied by music, energy and enormous crowds. Each evening gets started at 6:30pm with the daily bullfight, starring the bulls that ran that morning. Afterwards, gear up for a night of fireworks and all-night partying.
The festivities come to an end on July 14th with the singing of the traditional "pobre de mí." Literally meaning "poor me," the song laments the end of another year's festivities.
Learn more on the official Sanfermines festival website: www.sanfermin.com
Running of the Bulls Route
