Built-in fireplace unit
FIG. 1 is a top front perspective view of a built-in fireplace unit, showing my new design; 
     FIG. 2 is a front elevational view thereof; 
     FIG. 3 is a top plan view thereof; 
     FIG. 4 is a bottom plan view thereof; 
     FIG. 5 is an end view thereof, with the opposite end view being a mirror image of the view shown in FIG. 5; and 
     FIG. 6 is a rear elevational view thereof.