San Ildefonso-El Espinar Biosphere Reserve Nature · El Espinar, Comunidad de Ciudad y Tierra de Segovia, Segovia Unesco declared on 28 May 2013 the biosphere reserve of Real Sitio de San Ildefonso-El Espinar, 35,418 hectares on the northern slope of the Guadarrama shared between two municipalities that add up to some 15,500 inhabitants. Photo: Arturo Francisco Barbero (CC BY-SA 4.0) What to see and do in El Espinar