The Prime Group is a Chicago real estate developer that has spent more than two decades reworking Daniel Burnham’s Continental and Commercial National Bank Building at 208 South LaSalle Street, one piece at a time. It converted the lower twelve floors into a JW Marriott and opened floors 18 through 22 as the 232-key LaSalle Hotel in 2022. In June 2026 it took an interior demolition permit for the next phase, converting roughly 222,500 square feet of vacant office on floors 13 to 16 into 168 apartments, 51 of them rent-restricted under the city’s LaSalle Reimagined initiative, backed by $26 million in tax increment financing. Lucien Lagrange is lead architect and designer on that phase with LJC Design & Engineering as architect of record and Break Thru Enterprises as general contractor. The firm is also a joint venture partner on the 111 West Monroe conversion.
The 208 South LaSalle work described above is one chapter of a firm that has been developing since 1982, and the earlier chapters explain the appetite for it.
The Prime Group’s first national move was in retail. The company helped establish the factory outlet mall concept and became the largest owner and developer of outlet centres in the United States before that portfolio was absorbed into Simon Property Group. Its second was in seniors housing: the firm founded Brookdale Living Communities, which went public in 1997 and grew into the largest owner-operator of senior housing in the country. Both were bets on a building type before it had an established market, which is the same logic behind converting vacant Loop office floors into apartments forty years later.
In downtown Chicago the firm’s name sits on 77 West Wacker and on 181 South Dearborn, better known as Citadel Center. On the hospitality side it developed the J.W. Marriott Hotel and the Residence Inn Chicago Loop.
The current pipeline is unusually concentrated in conversions. Beyond the LaSalle Street phases, the company lists the RIU Grand Plaza Hotel, the conversion of the former Conrad Hotel into a Residence Inn, and the transformation of the BMO Harris office campus at 111 West Monroe into mixed-use residential and hotel space. The most consequential is the acquisition and redevelopment of the James R. Thompson Center, the Helmut Jahn building on Clark Street, which is to become Google’s Midwest headquarters.
The company’s stated mission runs to living, working, retail and industrial environments with a return on investment attached, and its self-description leans on planning, architecture and cost-effective financing as the three levers. On adaptive reuse at this scale the financing lever tends to be the one that decides whether a project happens, which is visible in the LaSalle Street phase: tax increment financing and a rent-restricted unit count are structural to the deal, not an afterthought.
The Prime Group describes itself as an owner, developer and operator across residential, commercial and hospitality assets, which is a wider remit than a pure developer and matters when a building is going to be held through a phased twenty-year repositioning rather than sold on completion.
