Firefighters battled the blaze on the 200 block of South Broad Street just after midnight.
Sprinklers activated, helping firefighters quickly get the upper hand.
The 22-story building is the former Equitable Trust building, built back in 1925. It was placed on the National Registry of Historic Landmarks in 1986.
The building is now home to a PNC bank branch, a law firm, and several other businesses.