The four-story former Gaviidae Common II building at 555 Nicollet Mall is getting a face-lift that will create new Class A office space while combining the structure with the adjacent 40-story RBC Plaza office tower.

"This is a premier address in downtown Minneapolis, but you don't feel that today," said Sonja Dusil, a real estate broker with Bloomington-based Cushman and Wakefield/NorthMarq, which manages the two buildings. "We're trying to build off of being in the heart of the city by adding larger window sizes in the offices that will be on the third and fourth floors."

The cost of the renovation wasn't disclosed. The two buildings were purchased last year by KBS REIT III of Newport Beach, Calif., for $126 million. After the project is completed in the third quarter, the combined buildings will be called RBC Plaza. The work is being done by RJM Construction of Minneapolis.

The renovation will convert the third and fourth floors of the Gaviidae building to 60,000 square feet of office space accessible through the RBC Plaza elevators. The fourth floor had been a food court, and the third floor had been offices.

The first and second Gaviidae floors will be devoted to retail stores, as they have been, and the first floor will be ­separated from the RBC Plaza by a glass wall with doors.

The lower level of Gaviidae will be remodeled to include a conference room, fitness center and locker rooms.

"We're taking an outdated mall from the 1980s, and converting it into the office lobby of a Class A office tower," Dusil said.

Steve Alexander • 612-673-4553