500 North Michigan Avenue Office-to-Residential Conversion

SOM designed 500 North Michigan as an office building in 1968. Skender started tearing out its interiors in July 2026 to make it 320 apartments.

Commonwealth Development Partners, a Connecticut firm, broke ground on the $162 million conversion on July 29 alongside Mayor Brandon Johnson and the city’s planning department. GREC Architects is the design architect. Delivery is targeted for late 2027.

Project Scope

Floors 3 through 23 were vacant office space and become residential. The unit mix is 256 market-rate and 64 affordable, and floors 2 through 5 pick up additional resident amenity programming. Level 24 stays mechanical.

The more interesting structural move is on top. A new 25th floor of indoor and outdoor amenity space with a rooftop pool adds 17 feet to a building that currently stands 304 feet, which means the existing frame and foundations had to be checked against a load case nobody designed for in 1968. A basement valet garage holds 68 cars.

Conversions live or die on floor plate depth and window line, and a Magnificent Mile tower from the late sixties is closer to workable than the deep-plate towers of the eighties. Even so, the plumbing risers, electrical distribution and unit-by-unit HVAC all have to be threaded through a structure with column spacing set for open office.

Why It Matters

Chicago has been trying to move office conversions from pilot to pipeline for four years, and the constraint has been the gap between what a vacant tower is worth as offices and what the conversion costs. City participation on the affordable component is how this one closed that gap. Sixty-four affordable units in a Streeterville tower is not a rounding error.

New York has run three conversion stop-work sweeps this summer, which is a reminder that the execution risk is real: these are occupied-adjacent, structurally invasive projects on buildings whose as-builts are often wrong. Chicago’s version is proceeding, and the industry will be watching what it costs per unit when the books close.

Project Team & Details