London without its Underground is unimaginable. Literally, since the movement across the city would become all but impossible; metaphorically, since the identity of the city, the mental image of the city we create as its inhabitants, is dictated by the experience of travelling in - and on - the tube. It is alien, different, otherworldly. Simultaneously of the city, located at its core, and displaced from the surface of it, it is London's alter ego.
Beyond the tedium of the everyday, the Underground holds its own romance; and yet, looking at what has been written about it, it is apparent that capturing its poetry is not that straightforward. Christian Wolmar's The Subterranean Railway charts out the history of the system, its spectacular progression from the development of the first underground railway in the world to the contemporary network of interlocking lines, still expanding; from the so-called 'cut-and-cover' tunnels dug right under the streets of London to the deep 'tube' lines which navigated the chalky depths of the city; from competing independent financial enterprises to a unified system under London Transport - Wolmar's book shows the sheer scale of invention, resourcefulness and risk-taking that created the system we know - and take for granted - today.
But there are also stories of the imagination. Tube Tales, a Sky production from 1999 told a series of fictional, often fantastical stories taking place in the tunnels; a train door closing a second too early changed the destiny of Gwyneth Paltrow's character in Sliding Doors; Tobias Hill's novel Underground confronted the mystery of a murder, caught on CCTV, with the life of an Underground employee in a story rich in melancholy; in Neverwhere, Neil Gaiman brought to life an angel named Islington, a train carriage on which Earl's Court would preside and the terrifying location of Knight's Bridge. Geoff Ryman's internet novel 253 catalogued a series of ordinary lives in their passage through the tunnels, journeying across the city. And yet, no one - historians, social theorists, filmmakers or novelists - seems to be clear on what it is that lends the Underground experience its slightly unreal, magical character.
Is it the Underground map - that abstract diagram, which retains only the most general similarities to the geography of the city above, reducing it to a series of cryptically named nodes between which there is nothing, no continuity but that of the journey itself? As one of the myths about the Underground has it, tourists have been known to take the tube from Leicester Square to Covent garden, failing to realise the proximity of the two, comprehending the city as a series of fragments, which, for all they know, never connect into a continuous city. To many of us living in it, London remains a constellation of islands suspended in a sea of travel, with endless flows of people haunting the dark tunnels of its yonder-side, in an inadvertent act of worship of those great Victorian machines changed the face of the world - the trains.
The Underground community is by default democratic. Carriages were fairly quickly made classless and the price of journey became the same for all; and the uniform seats do not favour a city boy over a goth or a bespectacled Asian grandmother visiting relatives. In December 1999 Tony Blair himself got on a tube train - and was promptly blanked by a fellow traveller, despite his media entourage. The woman claimed her rightful space of travel and felt no need to acknowledge what might have been perceived as extraordinary circumstance. It was just an everyday journey for her, and she was going to have it just as she pleased, in peace.
On the tube we face each other, literally, as the seats arrange us so, and decide how different or how similar we all are, rocking gently in time with the electric charge of the machine, waiting to arrive at our destinations, supremely aware of the unspoken rules of conduct, as if it were an edge of a knife, dangerous, with unnamed terrors lurking just around the corner, waiting to burst free of social conventions. Still, a group of young people has been known to travel on the Underground carrying signs offering free hugs; and there are stories circulating of endless parties being held on the Circle line, almost raising this 'line to nowhere' to the level of the ancient Greek agora - the public square where the idea of the rule of the people was once conceived.
The Underground is a unique movement system, and the repercussions on our perception of the city are manifold. Arguably, the most overlooked aspect is the regime the Underground imposes on our bodies, the habitual march of endless steps, which turns us into automata, anxious, annoyed, worn out, yet in those rare moments of release, able to look at ourselves and marvel.
If we look closer, we can see ourselves as particles in motion, fluid streams of humanity, 21st century cogs in this dark Victorian mechanism of urban transportation, confronting the machinery of the city itself, becoming one with its dark inside, travelling in a hurry, throughout the day, every day, only to meet London once again, over and over again.