More than 40 firefighters tackled a blaze on Tuesday at the former Museum of Mankind behind the Royal Academy of Arts in Piccadilly, the London Fire Brigade said.
Eight fire engines were sent to the three-story building on Burlington Gardens, after fire crews were alerted at 1:40 p.m.
Plumes of smoke could be seen billowing across the district, which is home to some of London’s most upmarket shops.
A fire brigade spokesman said it was too early to say what had caused the blaze, which has also set the roof of the building alight.
The former museum building, now owned by the Royal Academy and used for special exhibitions, was empty at the time of the fire which did not spread.
A spokesman for the Royal Academy said the damage appeared to have been limited to the roof and one gallery, but it was too early to say when the building might open again to the public.
USA TODAY, an exhibition of new American art from the Saatchi Gallery, is due to open in the building on Oct. 6, but a spokesman for the Saatchi gallery said it might be postponed because of the fire.