Subterranean Treasures: The Invisible Infrastructures That Keep Cities Working


Hidden infrastructures, tucked deep beneath the earth’s surface, often yield telling pasts and surprising discoveries.

These elaborate labyrinths of tunnels, pipelines, cables, tracks and transformers keep cities working seamlessly—but are typically unseen by the masses. Whether created centuries ago or recently renovated, they’re the structures and systems responsible for society’s transportation, electricity, water and telecommunication functionalities. Essentially, they’re the backbone of modern cities around the globe.

While some infrastructures have been abandoned or fallen into disuse, there are countless others busily operating below the asphalt. From cavernous sewers to original subway systems, we dig into the history and inner workings of the underground structures that help cities flourish.


A test run of the first Boston subway at Park Street Station on September 1, 1897. Photo courtesy of Boston Public Library.

Subsurface Transportation

The London Underground, which locals call “the Tube,” serves 275 stations throughout London.

Many American underground transit systems were first constructed during the late 19th and early 20th centuries to deliver services to city dwellers, and support rapid expansion and urban development. The country’s original underground subway line opened in Boston in 1897, more than three decades after the introduction of transportation systems in several European cities, including London. The line was created to relieve the congestion caused by streetcars above ground. A few years later, other densely populated cities such as New York and Philadelphia built similar systems that combined underground, surface and elevated electrified lines.

Today, the London Underground, which locals call “the Tube,” serves 275 stations throughout London. The New York City subway system has 472 stations spread throughout its boroughs and Boston handles an estimated 390 million rides per year. While these tunnels are responsible for transporting millions around the world’s largest cities daily, they’re virtually undetectable above ground.


Sectional view of Chicago’s water system from lake crib to pump works, 1871. Drawing courtesy of The Newberry Library.


Water running through hollowed wooden logs seems crude by today’s standards, but before iron pipes became the norm for water mains, it was the premier way to distribute this vital resource throughout American communities during the 1800s.

Chicago is often credited as revolutionizing the water system. To prevent waterborne illnesses from sewage flowing into the lake, the city reversed the Chicago River in 1900 to make it flow toward the Mississippi River. It also created an efficient twin-tunnel system, which supplied the city with water that extended two miles out into Lake Michigan.

Now, the Bureau of Water Supply provides just under one billion gallons of water per day to the Windy City and neighboring suburban communities. Through a sophisticated purification process, water is pressurized and pumped to homes and commercial properties throughout the nation’s third-largest city. Today, more than 250 million people in the U.S.—or approximately 90 percent of the population—get their water from community water systems, which supply water to the same population year-round.


During the mid-19th century, with rampant disease outbreaks caused by unsanitary conditions, sewer systems began to be regulated by specific laws in many developed countries.

Inconspicuous Sewers

Underground sewers are the sister structures to the water systems of the world. While there is archeological evidence of ancient forms of drainage systems, they weren’t underground, organized or as fully operational as they are today. Early iterations were simply ditches made alongside streets.

During the mid-19th century, with rampant disease outbreaks caused by unsanitary conditions, sewer systems began to be regulated by specific laws in many developed countries. In 1858, London experienced what is referred to as the “Great Stink,” an event during which hot weather conditions exacerbated the stench of untreated waste and industrial effluent on the banks of the Thames River, ultimately making people sick. Authorities decided to resolve the problem by hiring a civil engineer to devise an underground sewage system that moved the waste eastward along a series of interconnecting sewers that slanted towards channels beyond the metropolitan area.

That system still runs in London today, as do other similar versions throughout the world. In most cases, pipes from each house or commercial building flow to a sewer main that runs down the middle of the street, which can run up to 5 feet in diameter. The manholes people walk pass daily are there to allow access to the main for maintenance and repair purposes.


Con Edison crew working to restore power on Metro-North New Haven rail line. Photo courtesy of Con Edison’s Flickr.

Electric Power

Miles and miles of electric cables lie beneath the bustling streets of New York City. Most of the area gets its energy through Con Edison, a power company that has provided New Yorkers with electricity since 1823.

Currently, there are 95,270 miles of underground cables, 266,433 manholes and service boxes, and 41,564 underground transformers that fuel the city’s growth and contribute to its vast power grid.

Before energy reaches power sources in homes, it goes through a fundamentally seamless process. First, it’s sourced from either from wind, solar or generating stations. Next, the voltage is stepped up for transmission over wires. Then, it’s transmitted through power lines and the voltage is stepped down for distribution. Afterwards, via transformers, the current is stepped again in preparation of its final destination: an outlet near you.

The power company also supplies electricity to the city’s transit system, which is one of the vital threads that makes New York one of the most remarkable places to live and visit.


Signals transmitted from cables like these are sent to the electronics used in our homes and offices.

Concealed Telecommunications

Cabling provides the connections that are essential to unlocking our devices’ wireless capabilities.

Nowadays, grabbing a smartphone to make a call, surf the web or stream music has become second nature. Thanks to the advancement in telecommunications networks, it’s possible to have these indulgences at our fingertips.

However, many don’t understand how it all works. In a nutshell, there are companies throughout the U.S. and abroad that have developed complex underground systems where seemingly endless miles of fiber optic, copper and coaxial cables deliver television, telephone, wireless and internet services. These telecommunication services rely on vast infrastructure system that includes cell sites and distribution and switching facilities.

Cabling provides the connections that are essential to unlocking our devices’ wireless capabilities, whether they’re strung atop utility poles or via conduits underground. The signals transmitted from these cables are then sent to the electronics in our homes and offices.

Back to the Future

When it comes to the infrastructures that keep cities thriving, looking back helps us move forward. Engineers and city planners can take lessons from the past on how to improve the infrastructures that paved the way for future advancements. As technology continues to evolve, the structures housing the utilities of tomorrow will only become more efficient, resourceful and sustainable—ultimately, making our lives easier.


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