The tufa of the Hornillo River Nature · Tubilla del Agua, Páramos, Burgos Image of Tubilla del Agua, not of the place itself. The River Hornillo runs through the built-up area laying down calcareous tufa as it goes, a phenomenon that gave the village its name and that still forms steps and small falls among the vegetable plots on the valley floor. Photo: José Antonio Gil Martínez from Vigo, Spain (CC BY 2.0) What to see and do in Tubilla del Agua