Donald Brown, who co-founded a firm that would become the largest real estate company in D.C., has died.

The JBG Cos. co-founder died of cancer Wednesday at the age of 90, the Palm Beach Post reported. Brown in recent years lived with his wife, Ann Brown, in Palm Beach.

Brown represented the "B" in The JBG Cos., which would later become JBG Smith. Along with Benjamin Jacobs and Joseph Gildenhorn, he co-founded a real estate-focused law firm in 1956. The trio co-founded The JBG Cos. in the 1960s, and Brown served as principal until 1996, the Washington Business Journal reports.

"We are saddened by Don’s passing and will remember him as pioneer in the industry," JBG Smith CEO Matt Kelly said in a prepared statement. "He was a leader and a mentor in the community. Don’s inexhaustible capacity to give made him unique and special to all who knew him. Don will be missed, but his legacy will live on through the great work taking place at JBG Smith and through all the lives he touched. Our sincerest condolences go out to his family and friends."

Through its placemaking style of mixed-use development, JBG has helped transform D.C. neighborhoods such as Shaw and 14th Street that are now among the city's most popular corridors.

The JBG Cos. in 2017 merged with Vornado's D.C. business and launched a public company, JBG Smith. The REIT landed the biggest economic development prize in years in November when Amazon announced it would buy and lease property from JBG Smith for its second headquarters in Crystal City and Pentagon City.

Brown served as a mentor for younger real estate professionals who have become industry leaders. Walker & Dunlop CEO Willy Walker, in a 2018 interview with Bisnow, named Brown as one of his top mentors.

Brown has taught real estate at the Harvard Business School, the Yale School of Management and George Washington University's Graduate Business School. Brown moved to South Florida in the 1990s and focused on philanthropic causes, including as a donor and vice chairman of the board of not-for-profit theater company Palm Beach Dramaworks.

He is survived by his wife and two daughters, Cathy and Laura, and three grandchildren. The family will host a get-together at his Palm Beach home Friday at 4 p.m.