The mouth of the Adaja at the Duero Nature · Villanueva de Duero, Tierra de Medina, Valladolid The municipality occupies 37.29 square kilometres on the left bank of the Duero, some eighteen kilometres upstream of Valladolid, just where the valley of the Adaja opens up and delivers its waters to the great river. Photo: Lourdes Cardenal (CC BY-SA 4.0) What to see and do in Villanueva de Duero