Demolition on the one-story portion of the building on the corner of Market Street and Pennsylvania Avenue, next door to the Times Observer, began on Thursday.
Keith and Nate White of Keith White Excavating are knocking down the building, and loading the debris into large dumpsters.
Keith White said it must be done with care, as portions are connected structurally to the main building.
Over the years, the building has served as Warren's post office, a state liquor store, the AAA office, an insurance office and a hearing aid center.
The addition, which dates to the 1950s or 1960s, served as the headquarters of the local International Brotherhood of Electrical Workers and a tattoo parlor.
Jameson Shepherd, the general contractor for work on the building, said that while the addition is in terrible shape, possibly because of flooding over the pre-Kinzua Dam years, the main building was well built.
Still, he said, there is a tremendous amount of work remaining to restore the apartments, including drywall installation over old plaster walls.
Some of the interior woodwork still needs stripping, and the floors will be refinished.
Over 50 new energy efficient windows have been installed, Shepherd said, reducing traffic noise from Pennsylvania Avenue.
Looking at the building from the outside doesn't give a clue to the interior spaces. "The front apartment on the third floor is 1,600 square feet," Shepherd said. Many houses are smaller than that.
The building was purchased by Jessica Shepherd, but it is really a family business venture, Jameson said. Jessica is Jameson's sister. His brother Jacob is also working with him on the construction end of the venture.