The tau against the fire of San Antón Curiosity · Castrojeriz, Odra-Pisuerga, Burgos Image of Castrojeriz, not of the place itself. The Antonian monks tended pilgrims afflicted with ergotism, the so-called fire of San Antón, and handed out blessed objects marked with the tau-shaped cross, which was held to be a defence against plague and illness. Photo: José Antonio Gil Martínez from Vigo, Spain (CC BY 2.0) What to see and do in Castrojeriz