Chicago’s Old Main Post Office Is Reinvented as Office Space with Amenities and Details that Celebrate the Building’s History

In the 1930s, Amazon wasn’t a twinkle in anyone’s eye. Yet Americans had thousands of parcels delivered to their doors using mail-order catalogs and the U.S. Postal Service. Major department stores were headquartered in Chicago at the time, making the city bustle with mail-order activity. To keep up with the national demand, the Old Main Post Office Building at 433 W. Van Buren Street underwent a massive expansion 11 years after its completion in 1921, resulting in a 2.8 million-square-foot building that covers two city blocks.

“As the centerpiece of the American mail-order industry, this building has enormous significance to the city, state and country,” says Ashley Rogow, technical designer in Gensler’s Chicago office. “So many people were employed there, and it became a symbol of Chicago’s importance, distinguishing it from large East Coast cities, like New York.”

By 1996, the post office was too large for daily operations and the U.S. Postal Service abandoned the building. It sat vacant for two decades and began to decay with exterior pieces literally falling off onto the highway below. The iconic structure retained its grandeur, however, and was listed on the National Register of Historic Places in 2001. Developers, 601W Companies, purchased the site in 2016 and retained Gensler along with an extensive multi-discipline team to redevelop the site for office use. Even before programming began, the team replaced and reattached exterior limestone and terra cotta, as well as restored the main lobby area.

High Priorities

“One of the first and most important things we did was professionally photograph the interiors’ existing conditions,” Rogow recalls; she served as a designer on the adaptive-reuse project. “The photos document what we couldn’t salvage, and we used many of them as beautiful, almost ghostly art pieces inside the space. But in the grand lobby, we were able to restore nearly all original materials. It’s like stepping back in time to 1934.”

Art Deco pieces in the lobby include original wall panels, marble floors, plaster ceilings and gold mosaic tiles decorated with bronze medallions that adorn large alcoves. The medallions showcase all the different ways the mail was delivered: pony express, steam engine, plane, truck, postal carrier, etc.

Double-helix mail chutes cut through multiple levels, but code requirements didn’t allow open penetrations between floors. The team brainstormed unique scaffolding with safety systems so construction workers could insert decking inside the chutes and seal off each floor.

Packages formerly flew down the chutes onto tables lined with mail rollers to move the mail. The original rollers were unsafe, so Gensler sourced new rollers, flipped them vertically and backlit them to become a 3D, textural wall-art installation.

The team also saved several huge mail scales sunk into the floor, where mail carts were once rolled over and weighed in batches via old-fashioned dials. “The scales are like steam-punk sculptural elements,” Rogow notes. “We saved these really interesting artifacts and repurposed them in unique ways.”

From 1911 to 1966, the Post Office Department offered government-backed savings for individually held accounts. To hold deposits, the Chicago Old Main Post Office included multiple bank vaults. The largest, a steel-reinforced concrete box built into the first floor, had 6-foot, 8-inch by 8-foot, 8-inch vault doors weighing thousands of pounds. The team pinned open the colossal doors to be visible to the tenant, and the windowless vault can be used as a small office or storage space.

In the concierge area, small pieces of mail and antiques from the 1920s and ’30s sourced from across Chicago serve as reminders of days gone by.

“Our goal was to celebrate the building and its role in Chicago’s history,” Rogow asserts. “We wanted to continue the building’s legacy in every way possible.”