The River City Company has sold the office section of the building at 2 Aquarium Way by the Tennessee Aquarium to Marquis Apartment Investors.
Kim White of River City said the buyers are the operators of the nearby High Point Climbing and Fitness facility.
She said they were in need of office space.
The sales price was $890,000.
River City Company had bought the building back from the now-defunct Chattanooga History Center in 2016 for $2.2 million.
The History Center, under former director Daryl Black, had planned a history museum on the second floor, but it never opened.
A group is currently raising funds to put the former Medal of Honor Museum into that location as the Charles Coolidge Medal of Honor Heritage Center.
Ms. White said the Coolidge group was not interested in the office space.
She said the office area has a separate entrance.
Pucketts Restaurant is on the first floor of the building.