FOR LET: 36,000 square-foot cave in central Chicago. Three-story ceilings, cutting-edge fiber optic feeds, historic art deco ­setting. Ten pits available, perfect for lounging. Jackets not included.

When CME Group Inc.'s futures pits in the cavernous trading floor at the Chicago Board of Trade fall quiet next month, real estate broker Holly Duran will be working overtime to find a tenant to occupy a storied piece of U.S. financial history.

Prospective candidates could include big trading companies like BP PLC, whose hundreds of Chicago-based traders now occupy another former CME trading floor two blocks away, or tech firms. In Minneapolis, the tech incubator CoCo revitalized the former trading floor of the Grain Exchange.

"There's not a lot of high-ceiling unique office space in Chicago," said Duran, who has advised CME Group on its property holdings since 1980.

After more than eight decades of open-outcry grain futures trading at the landmark Chicago Board of Trade Building, trading ended July 6 at the art deco masterpiece that came to be seen as a symbol of turbulent capitalism reshaping the world.

The vast space once filled with ­thousands of arm-waving, hoarse-voiced traders, runners and clerks will be home to as-yet unknown new inhabitants lured, perhaps, by a superfast, sophisticated telecommunications network, or the retro charm of 10 octagonal pits where trading was conducted.

At an asking price of $30 a year per square foot, the 36,000 square-foot exchange floor — plus overhanging viewing galleries with another 15,000 square feet, and 27,000 square feet of related space on the upper floor — could go for more than $2 million a year.

"Depending on the user, the space may warrant a premium," said Duran. If a business needs more space, there is another 100,000 square feet or more available in the building. Financial services, social media, the start-up world, advertising or the financial-technology industry are all potential ­clients, she said.

Agricultural futures such as corn and wheat have been traded in downtown Chicago for a century and a half, and moved into the existing building when it was built in 1930. The floor that shut down last week dates back to 1982, a time when the Chicago Board of Trade was growing with the explosion of financial futures contracts, as well as commodities.

The CME sold the Chicago Board of Trade building in 2012 to a consortium including GlenStar Properties, and then signed a 15-year lease-back on the agricultural trading floor and other office space in the building, even though the faster and more efficient electronic matching of bids and offers meant that only 2 percent of futures volumes were floor-based. Keeping the floor open gave customers time to adjust to the volume shift to the screen, CME said.

The three-story interior space has the feel of a sports arena, but darker. Glassed-in galleries look down on the floor, and massive electronic price boards flicker red, green and yellow on all sides. The CME was among the last big exchanges in the world to shut down its pits.

Another exchange trading floor in the same CBOT building was taken over by investment firm Peak6 for its in-house trading operation; one smaller commodities exchange a few blocks away became a gym.

CME also had a large exchange floor on Chicago's South Wacker Drive, which was completely made-over for oil company BP, for its own trading floor.

"The large volume of space and the lack of windows created our toughest challenge," said Lisa Adkins, a project manager for Gensler architects who worked on the design for BP. They created mezzanines to extend workplace areas over the big room, and added an undulating ceiling for visual interest, she said.

Some renovations are also in order before new tenants arrive at the CBOT as soon as the fourth quarter, Duran said.

Windows long covered by vast price boards and displays will be revealed.

"It's like night and day once you pop in windows," Duran said. "You have this soaring height."