London is a tourist mecca. Thousands flood its streets each year, all year. They come “to see the sights.” Sights where there are those who are only too glad to take their money and show them the history and lore of the city’s well-known landmarks.

What these visitors do not know, let alone see, is the city that lies beneath the streets upon which they walk. If they did, they would tread carefully. For beneath there is a whole world of buried rivers, tunnels and chambers, caverns and passageways, crypts and sewers, to say nothing of the endlessly humming cables and pipes bringing water and electricity to the city’s inhabitants.

All Londoners tread upon the past. For centuries the dead have been buried beneath London. Their bones still lie there. So also do the remains of past worlds. The fabric of once-vibrant communities having become now-dormant fossils until some 21st-century explorer disturbs them. From prehistory to modern times, there is much that lies buried under the surface of a city that prides itself on being so up-to-date.

This subterranean companion to the city of the living is crowded with many centuries of past lives. It is also hot. As one descends, scientists tell us that the world beneath gets progressively hotter – 100 feet below is 19°C (66°F), and so on. As the latest building spurt around London produces ever-taller skyscrapers in a race for the heavens, it is as if there is a communal flight from what lies beneath and the possibility of falling into the inferno below.

And yet, this world below remains largely unknown. Not just to the average Londoner, but also to government officials and engineers. The region below London is largely unmapped, still shrouded in mystery, still full of surprises, still able to intrigue. The few maps that exist are rarely available to the public, especially given today’s ever-present dangers. That said, there has always been more than a hint of a forbidden zone to that land below. A place where no one should be permitted to enter, a place of danger, one that contains something secret, a place that perhaps holds strange forces at bay.

There have been, and still are, many fears and superstitions around what lies beneath London. But a subterranean place may also be one of safety. During the Second World War, London’s Underground stations became a second city:  a city within a city when at night the sirens sounded and the faint outlines of approaching Luftwaffe planes were to be seen against the evening sky. At such times, thousands of Londoners were seen heading underground, and to safety. The wartime government was so concerned at the sense of retreat implied in this that they made it clear that those who descended to avoid the bombs above must also ascend once the all-clear was given. What the politicians could not fathom was how deep the allure of the underground is, buried as it were somewhere in the human psyche, prone to rise once more when faced with a external threat of some kind.

Each day many millions of Londoners still go underground. The London Underground transport network has approximately 5 million passengers each day, who make 1.37 billion journeys each year. Many of these journeys pass deep under the ground.

The Tube has 270 stations spread over 250 miles of track, with almost half that underground. The deepest station is Hampstead, at nearly 200 feet below the surface. The longest escalator comes to ground from a station appropriately called Angel, with as its creaking stairway moves heavenwards, bringing thousands each day into the daylight. The Tube crosses the River Thames at various points but few riding on the trains that do so are aware of this. Few also are aware of the many stations on the network long since abandoned. They are known as “ghost stations.” Some remain remarkably intact; some still have the vague remains of the advertising that regaled its walls. To enter such a place is to see somewhere frozen in time. It is as if such a place is cursed by this world: one that will never again be used; never again be connected with life. It is truly a “ghost station.”

For many years there has been talk of other ghosts upon the network. Some stations are claimed to be haunted, notably Covent Garden. This would not surprise those who have ridden London’s trains for many years. Sadly, each year, approximately 50 people throw themselves before oncoming trains. This macabre statistic is made more curious still by the fact that most of these suicides occur on Monday mornings at the height of the rush hour. In a city such as London it is impossible not to live cheek-by-jowl with one’s fellow citizens and their concerns. Depression and anger, drunkenness and madness are all on display most days somewhere on the Tube. It is a moving collage of humanity, and all of humanity and its various humours are present there.

So what of faith? That too is present on the Tube, where so many people are to be found. I have seen many a woman — and it has been, for the most part, women — open a Bible seated on the train. I have seen a man standing holding a rosary absorbed in his devotions while a packed commuter carriage politely ignored him. I have seen two religious sisters sit in front of me and discreetly begin to say the Angelus only to be pleasantly surprised when I joined in. Their reaction makes me smile still such was its bewilderment, as if a visitation from another world had occurred. I have traveled with monks who, dressed in their monastic habits, and noted how the world reacted to them — mostly with cautious curiosity. I knew a man who was considering his vocation and whether to enter a particular monastery at a resort town on the South Coast. He boarded an underground train only to see the advertisement in front of him telling him, in no uncertain terms, to go immediately to that same seaside resort on the South Coast. Soon after, he entered the monastery, and, decades later, remains there. Another young woman was also boarding a train while praying to St. Thérèse of Lisieux for help in deciding whether to enter a Carmel. When the doors of the carriage closed behind her there was an overpowering and unmistakable smell of roses — traditionally an indication of the presence of the young saint. Needless to say, in due course, the young woman entered Carmel.

London’s hidden subterranean metropolis continues to expand. The latest project is an additional Tube line called Cross Rail. Work began upon it in 2009 and is due to finish later this year. Until recently, in the east of the city, there was an image watching over those who constructed the line. A statue of St. Barbara, patron saint of underground engineers, stood at the entrance where, daily, workers filed past. In a city not noted for piety, each day it became a popular devotion to touch the statue as one passed. So much was this the case that the statue today — now in the Museum of London — has no sword left in its hand.

So even the world beneath London in the myriad miles of tunnels, the vast subterranean passage ways, the monumental caverns, the forgotten rivers, the endless sewers — even here, there was, and no doubt is yet, somewhere, a visible sign indicating the Name to which all must bow whether in the skies above, or upon the earth, or in the worlds below.