Monday was the first day of the famous San Fermín festival in Pamplona, Spain. It is more commonly known as the running of the bulls.

This tradition dates back to 1591, when men would rush their cattle to be the first to the marketplace. Each morning this week, people will gather to run with the bulls as they race down the street, from pen to bullring, where there will be bullfights the rest of the day.

Though the festival is beloved by many — and glorified in Hemingway's The Sun Also Rises — some people are hoping that the sun will set on this tradition. On Saturday, animal activists lay on the ground outside the entrance to the Pamplona bullring, painted red and sporting bull horns. The activists, mainly from the animal welfare organizations People for the Ethical Treatment of Animals and AnimaNaturalis, held signs saying: “Pamplona’s streets are stained with bulls' blood." They are calling for an end to the bullfighting tradition in Spain, saying it abuses and harms the bulls.