Railways have had a dramatic impact on the environment, transforming both the natural and urban landscape. They destroyed homes and historic sites and ripped through the countryside, bringing pollution to previously unspoilt areas and serving industries that caused environmental damage to town and country alike. Although many people enthusiastically embraced the progress of the railways, their assault on the environment also provoked fierce opposition. Eventually they earned acceptance and even came to be regarded as part of the scenery. In fact, by the end of the twentieth century increasing pollution from roads meant that railways were almost universally seen as the green transport alternative. This topic looks at the sometimes-troubled relationship between railways and the environment, and how a great polluter turned green.