The Guareña and the site of El Coto Nature · Castrillo de la Guareña, La Guareña, Zamora Image of Castrillo de la Guareña, not of the place itself. The río Guareña crosses the municipal district in a predominantly flat landscape that ranges between 717 and 834 metres; at the spot of El Coto material of the Chalcolithic period appeared. Photo: David Perez (CC BY 4.0) What to see and do in Castrillo de la Guareña