The mountainous Apennine chain, forming a rugged spine along the slender Italian peninsula, is one of Italy's best-kept secrets. Nearly 400km in length, and ranging between 400m and 2000m above sea level, the exhilarating Great Apennines Trek (GEA) spends just over three weeks criss-crossing the central-north section of the range, following routes established by long-gone invaders and traders, and trodden by pilgrims and shepherds since time immemorial.