Abstract: A fireplace assembly comprises a smoke chamber and a firebox in fluid communication with the smoke chamber. A masonry casing partially surrounds the firebox, the casing having a pair of spaced-apart side walls which together define an opening to the firebox. In one aspect of the invention, a lintel supports at least one chimney breast block across the opening, the lintel extending between the side walls and being supported by the side walls. In another aspect of the invention, a damper is mounted above the smoke chamber. In another aspect of the invention, the firebox is comprised of a plurality of firebrick, a metal firebox frame for guiding installation of the firebrick, and insulation between the firebox frame and the firebrick. In yet another aspect of the invention, insulation surrounds the back and sidewalls of the firebox and smoke chamber.