The fire hit the old stock exchange in Copenhagen, one of the most famous buildings of the Danish capital, engulfing its tower, which collapsed onto the roof. There were no reports of injuries.
Footage released by local media showed people carrying large paintings out of the building to save them from the flames. The building was built in 1615.
The historic building, whose tower is shaped like the intertwined tails of four dragons, was undergoing renovations when the fire broke out on Tuesday.
The Dutch Renaissance-style building no longer houses the Danish Stock Exchange, but serves as the headquarters of the Danish Chamber of Commerce.
“A terrible scene awaits us. The stock market is burning”, wrote the Chamber of Commerce on X.
Copenhagen police have asked people to avoid driving in the inner city.