The fire happened downtown in a building on Columbia Street which housed three apartments and a law firm.
Fire crews were called to the building just after 9 pm on Sunday for reports of a fire.
When they arrived, they saw flames showing in the back of the building from the ground floor to the roof.
Crews were able to knock the fire down quickly, and luckily no one was inside at the time.
Most of the damage is reportedly to the exterior of the building.
":Because it was mostly an outside fire, most of the damage is contained to the outside…but there is some inside and we’re digging out the hotspots now.": Bangor’s Assistant Fire Chief, Scott Bostock told TV5 Sunday.
Tenants were kept out of the building until Monday morning while fire crews clean up the damage and secure the building.
There has been no word yet on what caused the fire: an investigation began as soon as the flames were subdued.