Church of Santa María de Castrillo Monument · Castrillo de la Valduerna, La Bañeza, León The parish church of a town set on the south-eastern foothills of the Sierra del Teleno, in the Duerna valley. Beside it the municipality preserves a hermitage and several watermills on the river's course. Photo: Rodelar (CC BY-SA 4.0) What to see and do in Castrillo de la Valduerna