Find an old mantel from an antique store for the real look of an old fireplace. Look for any kind you can find, not worrying about the type of finish it has since you can simply paint it later.
Clean up the mantel once you get it home, removing any loose paint with sandpaper, and painting it to match the décor of your room. Let it dry overnight before trying to move it.
Find the studs in your wall where you want to install the mantel, using a stud finder. Mark the wall lightly at the stud positions with a pencil, high enough so you can see it even when the mantle is in place.
Hold the mantel against the wall; mark a few spots to outline where the framework should be placed along the lines where you marked the studs' positions. Drill four small pilot holes through the mantel at the top corners and bottom sides. Screw the mantle into the wall with 3-inch wood screws.
Measure the inside opening of the mantel where a fireplace would have been. Cut a section of brick or rock wallpaper with scissors to fit in the opening, making it a ¼-inch larger on all sides to slide into the gap between the wall and the mantel frame.
Mount the wallpaper either by removing the back paper and sticking it into position on the wall or by wetting it, depending on the type of wallpaper you purchased. Try to find wallpaper that is not glossy.
Set bricks into position at the base of the mantel from the wall out about 12 to 18 inches and about 24 inches wide. Stack them flat and into any pattern you like, keeping them close together, forming a hearth.
Decorate your artificial fireplace by adding a small decorative fire screen to sit on the bricks. Add a few fireplace tools and don't forget to set a bunch of candles on a fireproof tray in your fireplace.