Once every winter, in the village of San Bartolome de Pinares in Avila, north-west of Madrid, residents celebrate Luminarias, a bonfire festival honouring St Anthony the Abbot.
At this year's festival, which took place on Monday, villagers watched in awe as the flames roared up, and horses and riders began leaping through the flames.
St Anthony the Abbot is the patron saint of domestic animals, and some townspeople say the celebration dates back five centuries to when the plague was fought with Roman Catholic rituals that used the smoke for purification.
San Bartolome has continued to keep the festival alive with religious intensity and unswerving pride, fending off criticism from animal rights groups, reported the Associated Press.
One group, Observatory of Justice and Animal Defence, even filed a complaint with the regional government in 2013. However, veterinarians sent by the authorities could not find any injuries on the horses from the bonfires.
"Not one burn, not even one harmed horse," said Mayor Maria Jesus Martin, who insists that no horse is forced to jump over the flames.