The building the National Association of Realtors has called home for 56 years is getting a much-needed facelift.

The real estate trade group is planning a massive $45M renovation and expansion of the 12-story building at 430 North Michigan that will dramatically redefine it and bring a new look to the Magnificent Mile by adding to the real estate activity in what is arguably the hottest part of downtown.

NAR will renovate all 12 floors, upgrade the building's elevators and lobby and modernize its infrastructure. The group is also building a rooftop conference center, inspired by the nearby Apple Store at 401 North Michigan. This will be the second time the building is vertically expanded. The Realtors Building was originally 10 stories when it debuted in 1962; two more floors were added in 1991.

NAR's partner in the project is ONE Development, a new development and design arm of GNP Realty Partners. ONE Development President John Gagliardo said renovations will begin in fall 2018.

"When we’re done, 430 North Michigan will be a world-class asset and headquarters befitting the Realtors,” Gagliardo said.

NAR CEO Bob Goldberg said the renovations will allow the group to call the building home for another 40 years. The project is notable because the building is fully leased to an assortment of trade groups including the Chicago Association of Realtors, which cut the ribbon on its new headquarters last year.

The southern edge of the Mag Mile, bounded by Michigan Avenue and East Wacker Drive, has become a hotbed of real estate activity. Walton Street Capital bought 401 North Michigan from Zeller Realty in a $370M deal in May 2017, and is seeking buyers for the newly built Apple Store. Zeller completed a $255M sale of the Wrigley Building to billionaire Joe Mansueto last week. Across the street from the Realtors Building, Golub is in the process of redeveloping Tribune Tower from offices to condos, and is building Chicago's second-tallest building on an adjacent parking lot.