Cueva Huerta Nature · Teverga, Oviedo, Asturias Image of Teverga, not of the place itself. Located in the gorge of the Foz de la Estrechura, near the AS-228 road between Páramo and Fresnedo, this cave system, formed by the Valdesampedro river, has 14.5 kilometres of surveyed galleries, making it the second-largest cave system in Asturias by extent, after the Red de Toneyu, at 19 kilometres. It is part of a singular karst complex bringing together a gorge, a sinkhole, a cave and several underground watercourses; its best-known stretches are the main gallery, the zero-point chamber, the old gallery -with the formations known as the cathedrals- and the San Martín gallery. It shelters protected colonies of cave bats. It was declared a Natural Monument on 29 August 2002 and can only be visited with a guide. Photo: Omarete (CC BY-SA 2.5 es) What to see and do in Teverga