CHICAGO—601W. Cos. revealed its plans for Chicago's historic Main Post Office yesterday, one of the city's most anticipated projects and at more than 2.8 million square feet currently the largest redevelopment in the nation. Spanning three city blocks and five acres, the building sits just over the Eisenhower Expressway at 433 W. Van Buren St. Generations of Chicago-area residents have driven under the landmark property, which will soon open as a new business and retail hub.

The design, led by Gensler Chicago, will preserve the building's historical character. And at a cost of more than $600 million, the developer will transform its 250,000 square-foot floorplates into office space, enough for an estimated 15,000 workers. They will enjoy ceiling heights of up to 19 feet, an important consideration for companies that want to provide employees with sweeping views and natural light.

“We fully recognize the historical significance of this building,” says Brian Whiting, president of The Telos Group, which oversees strategic positioning and leasing of the office space. “When the Post Office was built, Chicago was the center of catalog retail sales and the building was designed to handle fulfillment for the largest operators, including Sears, Roebuck & Co. and Montgomery Ward. Fittingly, the Post Office will once again serve to promote the commerce industry, including the e-commerce companies that have replaced catalog houses, but this time with cutting-edge office space.”