The trace of a mysterious and tragic mining railway crosses the lush oak forest of the Sierra del Madero, on its ascent to the unique site created by the old Petra oligistine mine, today embellished and hidden under a turquoise lagoon.

Basic Facts
	3,48 Km
	Ólvega. Soria. Castile and León
	Trekkers, cyclists, suitable for people with reduced mobility
	Asphalt
	41.769808, -1.992505
	41.750693, -1.966064