When you walk into the Merchandise Mart in Chicago, you don’t just see a building-you step into a story that began with ambition, survived collapse, and reinvented itself in ways no one expected. At 4.2 million square feet, it’s the largest commercial building in the world by floor area. But size isn’t what makes it legendary. It’s the way this Art Deco titan refused to fade, even as the world around it changed.
The Birth of a Giant
In 1930, the Merchandise Mart opened as the wholesale heart of American commerce. Built by Marshall Field & Co. and the Chicago & North Western Railway, it was designed to bring order to the chaos of Chicago’s sprawling wholesale markets. Before the Mart, merchants hauled goods across city blocks in horse-drawn wagons. The Mart centralized it all under one roof-over 1,500 showrooms, 300 miles of corridors, and a freight elevator system that moved goods faster than any building before it.
The architecture? Pure Art Deco. Steel frames wrapped in limestone and aluminum, geometric patterns carved into facades, and soaring atriums lit by skylights. The building’s signature feature-the 17-story tower with its stepped crown-wasn’t just for show. It housed the building’s original radio tower, broadcasting signals across the Midwest. The interior’s terrazzo floors, brass railings, and custom light fixtures were all designed to impress buyers and convey prestige. Even the elevators had velvet curtains and attendants in uniforms. This wasn’t just a warehouse. It was a temple of commerce.
When the World Changed
The Mart didn’t just survive the Great Depression-it thrived. By 1935, it was handling 40% of all U.S. wholesale goods. But after World War II, retail shifted. Department stores like Marshall Field’s started selling directly to consumers. The rise of suburbs and shopping malls made centralized wholesale obsolete. By the 1970s, the Mart was half-empty. Its future looked grim.
Then came a twist no one saw coming. In 1979, the University of Chicago’s development arm bought the building for $120 million. It wasn’t an academic move-it was a bet. They saw potential in its structure: thick load-bearing walls, massive floor plates, and central location. They didn’t want to turn it into classrooms. They wanted to turn it into something new.
The Tech Turnaround
By the 2000s, the Mart had become a magnet for tech companies. Why? Because it had something Silicon Valley couldn’t replicate: space, scale, and soul. Google moved in a wing in 2012. Salesforce followed in 2016. By 2020, over 30 tech firms occupied over 1.2 million square feet. The building now hosts AI startups, cybersecurity labs, and even a robotics incubator run by the University of Illinois.
Modern offices here don’t replace the old. They work around it. Original marble lobbies still greet visitors. The grand staircase-once used by garment buyers-is now a spot for coffee breaks and networking. The old freight elevators? Repurposed into vertical gardens and art installations. The building’s DNA didn’t change. It just added new layers.
One of the most surprising adaptations? The 200,000-square-foot rooftop. Once a storage yard for unsold goods, it’s now a solar array that powers 15% of the building. Rainwater collected from the roof feeds into a closed-loop cooling system. The Mart doesn’t just house tech-it runs on it.
Why It Still Matters
Most historic buildings are preserved as museums. The Merchandise Mart is alive. It’s not just a relic. It’s a working machine. You’ll find architects sketching on the 14th floor, coders debugging in the basement, and fashion designers setting up pop-up showrooms in the old showroom halls. It’s a hybrid of old and new that doesn’t try to be trendy-it just works.
Compare it to other historic buildings. The Empire State Building is iconic, but it’s mostly offices and tourism. The Flatiron Building is a landmark, but it’s too small to adapt. The Merchandise Mart is different. It never stopped evolving. Its 1930s structure now supports 2026’s cloud infrastructure. Its Art Deco lines frame LED screens. Its freight tunnels now carry data cables.
What You’ll See Today
Walk through the main entrance on North Wells Street. Look up. The ceiling is still lined with the original bronze lighting fixtures. The floor? Still terrazzo, worn smooth by decades of footsteps. The grand staircase? Still used daily-not for fashion shows anymore, but for startup pitch nights and coding workshops.
On the 12th floor, you’ll find the old showroom of the American Radiator Company. Now it’s a co-working space for 300 freelancers. On the 20th, the former textile warehouse is now a data center with liquid-cooled servers. Even the basement, once filled with crates of wool and lace, now houses a server farm for a Chicago-based AI startup that processes medical imaging for hospitals nationwide.
There’s a small exhibit near the main elevator bank: a wall of black-and-white photos showing buyers from the 1930s holding fabric swatches. Next to them, a digital screen shows real-time data from the building’s energy systems. One shows the number of devices connected to the building’s Wi-Fi-over 8,500. The other tracks carbon savings from the rooftop solar panels-over 1,200 tons since 2018.
The Bigger Picture
The Merchandise Mart isn’t just a Chicago story. It’s a model for how cities can hold onto their history without freezing it in time. Other cities try to restore old buildings to their original state. Chicago chose to let the building keep changing. That’s why it’s still relevant. That’s why it’s still full.
It proves that architecture doesn’t need to be preserved-it needs to be reused. The Art Deco lines aren’t decorative here. They’re functional. They hold up the weight of modern tech. The building didn’t become a museum. It became a living thing.
Today, over 30,000 people work in the Merchandise Mart. Every day, 15,000 visitors walk through its doors. It’s not just a building. It’s a community. A marketplace. A lab. A monument. And it’s still growing.
Is the Merchandise Mart open to the public?
Yes. While much of the building houses private offices, the main lobby, the Riverwalk entrance, and the Merchandise Mart Public Market are open daily. You can walk through the grand halls, visit the food hall on the ground floor, and explore rotating art exhibits in the atrium. Guided architecture tours run on weekends and are free with registration.
What makes the Merchandise Mart the largest commercial building in the world?
It holds the title based on total floor area: 4.2 million square feet. That’s larger than the Pentagon, the Empire State Building, and the Houston Astrodome combined. It has 120 elevators, 11 miles of loading docks, and 300 miles of internal corridors. No other building-commercial or otherwise-has this scale under one roof.
Was the Merchandise Mart always owned by the University of Chicago?
No. It was originally built and owned by Marshall Field & Co. and the Chicago & North Western Railway. After financial struggles in the 1970s, it was sold in 1979 to the University of Chicago’s development arm, which still owns it today. The university manages it as a commercial asset, not an academic facility.
Can you tour the Art Deco details inside?
Absolutely. The building’s original Art Deco features are preserved and highlighted. Look for the bronze elevator doors with geometric patterns, the marble staircases with inlaid metal trim, and the ceiling murals in the main atrium. Many were restored in the 2010s using original 1930s blueprints. The best spot to see them? The main lobby during daylight hours-natural light reveals the craftsmanship best.
How has the building adapted to modern tech needs?
The building’s thick concrete walls and massive floor-to-ceiling heights made it ideal for data centers. Over 200 miles of fiber-optic cable now run through old freight tunnels. The HVAC system was upgraded with AI-driven cooling. Rooftop solar panels generate 1.8 megawatts of power. Even the elevators were retrofitted with smart sensors that predict maintenance before breakdowns happen. It’s a 90-year-old building running on 21st-century tech.