CTA el train

When we think of Chicago architecture, surely for many of us the skyline rising above comes to our mind. But the architecture of Chicago is actually very much below our feet, too. Many layers of tunnels, passages, sewers, pipes, and other infrastructural elements criss-cross below the streets of downtown Chicago. Let's delve into the depths of Chicago's underground layer.

The Pedway System 



The most user-friendly layer of Chicago's underground is the Pedway System. The word "Pedway" is short for "pedestrian way" as this collection of mostly basement-like hallways connect buildings, train stations, and underground parking structures downtown. And some part of the Pedway is "skybridge" on the second floor, and also on ground level it cuts through lobbies. I found the system so helpful for avoiding the cold, heat, rain or snow, that my company, Chicago Detours, made a map of the system

Underground Streets

Probably the most viewed portion of Chicago's underground would be the underground streets, such as Lower Wacker or Lower Michigan. I say this is the most viewed simply because of the Batman car-chase scenes, meaning millions of people around the world have seen it but likely have no idea what this dark concrete space actually is. Our multi-layered city has lower levels of streets throughout some parts of downtown and north of the river because it allows for the freight transport and trash disposal to easily access skyscrapers, thus making street-level less trafficked and more welcome and pleasant to all. Some layers are even


A great thing about the multiple layers is that it keeps the trash away from people, and that means....it keeps the rats away as well. Under our feet in downtown Chicago are of course the sewers, and while no human should actually want to explore these, it is where our population of 1 million rats live, which is really quite reasonable for a city of our size (you don't want to know how many are in NYC).

El Lines and Abandoned Freight Train Tunnels

Far below the Pedway and the underground blue and red El-lines in the Loop, one cannot access the abandoned freight train tunnels. Used primarily for the transportation of coal in the early 1900s, they were closed in the 1970s. People began to forget they were even there until a disastrous puncture of a tunnel in the 1992. This tunnel crosses from the Merchandise Mart underneath the north branch of the Chicago River to the Loop, and the puncture caused massive flooding in basements throughout downtown. After that the underground freight tunnels have mostly been sealed off. A small amount of cable car tunnels that are underground, too have been sealed off as well.

Water Tower Pumping Station


Historic Water Tower

According to WBEZ, the Pumping Station by the Historic Water Tower of Michigan Avenue was fed via a five-foot tall brick-lined tunnel that reached underground and out to a water intake crib. It's still under there somewhere!

The TARP Tunnel System

The least-known or understood feature of the Chicago underground would be the TARP system of giant tunnels. In the Chicago style of "make no little plans," the city has undergone one of the largest and longest civil engineering projects in American history. Billions have been spent on these tunnels and resevoirs that keep stormwater runoff from contaminating the lake, and would save the city in the event of extreme flood conditions. The tunnels are not so much under downtown, but rather stretch miles into the edges of the city. 

You never quite know what's underneath your feet in Chicago. Or what's above you, for that matter.