In 1863, London opened the Metropolitan Railway, the world’s first underground line, in an effort to reduce street traffic. Its roots can be traced back two decades to the construction of the world’s first under-river tunnel beneath the Thames, which quickly became a popular pedestrian destination and a major tourist attraction.

The London Underground was originally made up of tracks dug slightly below the surface and then covered over. However, as technology progressed and trains switched from steam to electric power, the lines became deeper. The ground beneath Londoners’ feet now hums with an extensive network of tube lines that quickly, efficiently, and invisibly ferry people around the city. Putting infrastructure underground has a lot of appeal, according to Bradley Garrett, a cultural geographer at University College Dublin and author of Subterranean London. He continues by stating that humans prefer things to run in the background. It gives the appearance of being seamless.

No one has proposed burying all of the world’s roads, not even Musk. But what if we relocated them all below ground? Imagining the impact of this in an era of increasing urbanization, rising inequality, and climate change raises important questions about how our global transportation system is evolving and prompts us to consider where we really want it to go.