French Cleat Video
Instead of ruining a piece by drilling holes and putting screws through it to hold it to the wall, try a French cleat. The French cleat can mount objects, such as mantles, to the wall without the use of unsightly fasteners.
What is a French cleat? It is two pieces of material that interlock with each other. It can be made from wood or metal. Use it to mount picture, plate, mantel, etc. to a wall. To make one out of wood, set your circular saw to 45 degrees and rip a 1 x 3 in half down the length of the board. Attach one of the pieces to the wall with the V facing up. The other piece gets attached the opposite way on the object being hung. Slide the two pieces together and you will have an interlocking mount.
Great for hanging objects without having nails or screws showing.