It is almost certain that you recently interacted closely with an invisible giant, as the Harvard landscape ecologist Richard T T Forman has described it. Others have called roads 'the single most destructive element in the process of habitat fragmentation', declaring that 'Few forces have been more influential in modifying the Earth than transportation.' Yet you probably didn't even notice. An expansive feature that snaps the globe but is effectively invisible: the vast network of transportation infrastructure ?" all the railways, canals but also, most significantly, roads. Roads are everywhere, forming an almost inconceivably complex system, an endless, ever-expanding, interconnected grid that facilitates the movement and exchange of people and goods over vast areas. This colossal structure is probably the greatest ever cultural artefact, a requirement and precondition for human development. For us, roads are essential connectors, linking places and purpose. But almost eve