In the 2000s, London’s government asked artist Mark Wallinger to make an art installation commemorating the Tube’s 150th anniversary. Wallinger chose to create a labyrinth for each of the city’s 270 underground stations, with each labyrinth embodying a unique geometric design and meaning.

These labyrinths are often in plain view, yet they often go unnoticed by the thousands of commuters and tourists who pour through London’s subway system each day. The hidden-in-plain-sight imagery of the designs is a fitting metaphor for the labyrinthine nature of the underground transportation system itself, and for the wider city environment, which can often seem like an urban maze.

But the labyrinths are also, according to the artist, a spiritual metaphor for the daily journey commuters embark upon while traveling through the city. They also have a much broader meaning, as throughout history the labyrinth has been a symbol of the journeys of life itself.