A fire official says there did not appear to be a connection between the two-alarm fire on the 28th floor of the Equitable Building and the Occupy Wall Street protests at nearby Zuccotti Park.
Dozens of fire trucks were on the street near the building at Broadway and Pine Street.
The property is listed as a National Historic Landmark because of its significance as the headquarters of "one of the insurance industry's earliest leaders."
The building's website lists the state's attorney general's office, Bank of New York and Alliance for Downtown NY as tenants.
Firefighters were seen breaking windows of the building.
No injuries have been reported.