When people walk through the busy streets of downtown Atlanta, they might not realize that an entire world exists just a few feet below their shoes. This hidden area is not a myth or a movie set. It is a real place with a history that spans over a hundred years. Often called the “city beneath the streets,” this underground world was created by accident during a time when Atlanta was growing faster than its roads could handle.
Why the City Went Underground
In the early 20th century, Atlanta faced a major problem: traffic. At the time, railroads were the main way people and goods moved around. However, the train tracks were at the same level as the dirt roads where people walked and drove horse-drawn carriages. This created dangerous situations and constant delays.
To solve this, city leaders decided to build bridges, known as viaducts, over the tracks. Between 1927 and 1929, a massive engineering effort called the “Twin Viaducts” project took place. This project raised the street level by about 15 to 20 feet. Instead of tearing down the old buildings, the city simply built the new roads right on top of the original ground floors.
As a result, the first floors of many shops became basements. Merchants adapted by moving their main entrances to the second floor, which was now the new street level. The “Twin viaducts project aimed to separate traffic levels entirely,” as historical records show. By elevating the roads, the city created a seamless grid for cars while keeping the trains moving safely below.
Life in the Shadows
For decades, this lower level was largely forgotten by the general public. While the city above grew with skyscrapers and modern cars, the area below remained frozen in time. During the Prohibition era in the 1920s and 30s, when alcohol was illegal in the United States, these hidden spaces found a new purpose.
Because they were tucked away from the eyes of the police, many of these “basements” became speakeasies and hidden music joints. People would sneak downstairs to enjoy music and illegal drinks. The dark, quiet tunnels provided the perfect cover for a secret nightlife that most residents above never knew existed.
The Great Rediscovery
The underground area stayed hidden until the late 1960s. Two graduates from Georgia Tech noticed the preserved architecture beneath the viaducts and saw an opportunity. They discovered that the original brickwork, granite archways, and even gas street lamps from the 1800s were still intact.
In 1969, “Underground Atlanta” officially opened as a shopping and entertainment district. It was an instant hit. For a few years, it was the center of Atlanta’s nightlife. One historian noted that “for a brief shining moment, the novel approach lured revelers” by the millions. The district was famous for its Victorian-era style and unique atmosphere that felt like stepping back into the 19th century.
More Than Just Shops: The Giant Sewer Tunnels
While the “Underground Atlanta” district is the most famous part of this hidden world, it is not the only thing beneath the surface. Deep under the city’s Westside lies an engineering marvel called the West Area Combined Sewer Overflow Tunnel.
This is not a typical sewer pipe. It is a massive hole drilled into solid rock, about 20 stories below the ground. It is 24 feet wide and more than eight miles long. This tunnel was a part of a 4-billion-dollar project to help manage the city’s water systems and prevent flooding. It is one of the most ambitious engineering projects in the history of Georgia, though very few people will ever see it in person.
The Famous Krog Street Tunnel
Further east, another type of tunnel serves as a bridge between neighborhoods like Cabbagetown and Inman Park. The Krog Street Tunnel was built in 1913 to link these communities across a busy railway line. Today, it is known worldwide as a “living canvas” for street art.
Almost every inch of the tunnel is covered in colorful graffiti, messages, and murals. Because artists add new work every day, the tunnel looks different every time someone visits. It has become a symbol of Atlanta’s creative spirit and a place where the community gathers to share art and messages.
| Feature | Underground Atlanta | Krog Street Tunnel | Sewer Tunnel |
| Primary Use | Shopping & History | Street Art & Transit | Water Management |
| Year Built | 1927–1929 (Raised) | 1913 | Early 2000s |
| Access | Public (Downtown) | Public (Eastside) | Restricted |
| Defining Trait | Original Storefronts | Graffiti & Murals | Massive Scale |
The Future of the Underground
Today, the historic Underground Atlanta district is undergoing another big change. While it has struggled with vacancy in recent years, new developers are working to turn it into a mixed-use space with apartments, offices, and new galleries.
The goal is to preserve the history while making the space useful for modern residents. The Zero Mile Post, which marks the center of old Atlanta from before 1850, still sits quietly under a viaduct. It serves as a reminder that the city’s heart is literally buried beneath the concrete of the modern world.
Atlanta is a city that has always built on top of its past. From the ruins of the Civil War to the elevation of the streets in the 1920s, each era leaves a layer behind. Exploring these tunnels is like reading a history book made of brick and mortar. Whether it is the artistic walls of Krog Street or the hidden speakeasies of the Five Points neighborhood, the underground world proves that there is always more to a city than what meets the eye.
