The fire devastated the 15,000-square-foot home of Peggy Cooper Cafritz, a political activist, former school board president and one of the founders of the Duke Ellington School of the Arts.
Over two decades, Mr Cafritz had amassed a collection of works by important artists including Kara Walker, Kerry James Marshall, Carrie Mae Weems, El Anatsui, Shinique Smith and Yinka Shonibare.
The Nigerian artist Shonibare will be the subject of a major exhibition at the Smithsonian's National Museum of African Art, beginning in November.
A preliminary report issued by local fire officials sought to reassure city residents that the Cafritz fire, whose cause is unknown, involved a unique set of circumstances and challenges.
Officials attributed the spread of the blaze to the house's unusually large size, and its remote location at the top of a steep hill which made it impossible to siphon water from multiple mains sources as firefighters prefer to do, according to the report.
The City Council is expected to hold a hearing on the fire in mid-September.