Trekker Zay Harding takes on an epic journey across one of the world’s biggest railway networks. These railways were built during the 19th century by the British to move troops and raw materials across the land, and ultimately played a role in the independence of the country a century later. The railway tracks are some of the oldest and longest you’ll find anywhere in the world, and train travel doesn’t get any tougher than this in a country with a population of over 1.2 billion.