Vía Verde de la Sierra Nature · Olvera, Sierra de Cádiz, Cádiz Former railway line converted into a cycling and hiking route between Olvera and Puerto Serrano, featuring the Peñón de Zaframagón, a Special Protection Area for Birds since 2002 for its colony of griffon vultures. ZEPA desde 2002 Photo: Fernando Cárdenas (Cárdenas) (CC BY-SA 2.5) What to see and do in Olvera