James Loewenberg, who designed and developed buildings that encompassed 45,000 residential units and more than 500,000 sq ft of commercial space along Chicago's North Lake Shore Drive, died Oct. 14 of pancreatic cancer at age 86, said Magellan Development Group, the company he co-founded and led with partner Joel Carlins.

Magellan is known for its development of Lakeshore East, a 28-acre, $4-billion neighborhood east of Michigan Ave. that is built on the former site of the Illinois Central Railroad's old Chicago yards. Loewenberg, an architect turned developer, was its co-CEO with Carlins until last year.

Loewenberg and Carlins had the vision to develop a two-level neighborhood on the parcel and started building there in the 1990s. What would become Lakeshore East includes multiple residential buildings, a park and two distinctive condominium skyscrapers, Aqua and Vista. Both towers were designed by Jeanne Gang, who the Magellan chiefs first picked in 2007 even though her firm, Studio Gang Architects, had never designed a high-rise before.

"Jim trusted me and I will always hold a special spot in my heart given the creative opportunity he gave me with my first high-rise, Aqua, and most recently my tallest high-rise Vista," says Gang, founding principal and partner at the firm. "He was not only a client, but a mentor, a collaborator and a friend as well. Our whole team at Studio Gang appreciated his can-do attitude and his deep knowledge of high-rise construction that he shared generously with all of us. His love for design paired with his Chicago pragmatism helped ambitious ideas become realities.”

Loewenberg followed his architect father, Max, into the business and joined family firm Loewenberg Architects after receiving his bachelor’s degree in architecture from the Massachusetts Institute of Technology.

Over six decades, Loewenberg showed an aptitude for the business side of development as well as design and eventually grew the  firm founded in 1919 to include a development unit.

Loewenberg then merged with Carlins' firm in 2006 after years of collaboration that started with the first Lakeshore East developments in the 1990s. Loewenberg’s other developments include Gallery on Wells and the Wolf Point West apartments.

He was chosen to receive the Urban Land Institute’s Chicago Lifetime achievement award in 2009.

Loewenberg also was known for mentoring an entire generation of Chicago real estate and design professionals, particularly women, since the 1960s.

"Jim Loewenberg gave me my very first job in real estate development and kickstarted a 20-plus year career for me in this business," says Tricia Van Horn, vice president of marketing and communications at Related Midwest. "I was given unprecedented opportunities to learn the ins and outs of architecture, design, development, leasing and sales directly from Jim and his decades of expertise. He was always willing to share his knowledge, invite me to the table and listen to my ideas and strategies and had an incredible ability to see the talents within each individual, and lift up many underrepresented communities including women in real estate."

Loewenberg and Carlins stepped down in December, relinquishing the CEO title to David Carlins, Joel's son.  Robin Loewenberg Tebbe, who had been Magellan's chief marketing officer, now manages the family's charitable trust. Loewenberg grandson, J.R. Berger, is still a principal at Magellan.

"Jim Loewenberg was a great man of great integrity and innovation in the real estate community,” David Carlins said in a statement. “His work had deep significance within our beautiful city and it will remain his legacy."