Eloy Alonso/Reuters
Thrill seekers take part in the festival's "Encierro," or Running of the Bulls, in which bulls are let loose when the clock strikes 8 a.m. The purpose of this exercises is one born out of necessity - to get the bulls from their corral into the bullring, which is 2,706 feet away.
While the event is usually over in a few minutes, it attracts hundreds of thousands of visitors to the tiny town each year.
Check out the wild images below for a look into this deep-rooted tradition, which is said to have originated in the early 14th century.